I've compiled an extended list of Cheats and Commands

Summary of TwistedMexican's Awesome Cheats! http://www.sherv.net/cm/emo/funny/2/dancing-banana-homer-simpson-smiley-emoticon.gif
CAUTION: Using cheats of any nature to affect a game's normal functioning has the potential to cause bugs, crashes, errors, or corruption. Use extreme caution when using any cheats and as a general rule: always make backups of your saves before using.

A mod by TwistedMexican supplies an in-game cheat to unlock lot and community objects!
Refer here and here in the thread for a list of various individual object IDs.

You can view TwistedMexican's Wiki with an index of current cheats here


The Official Cheats (Ones that EA themselves released)

• “testingcheats true”--Super important, this one will need to be activated for just about every other cheat. Useful in conjunction with other commands, and enables the SHIFT + LEFT CLICK on sims, mailboxes, and objects.
  
• “motherlode”--50,000 simoleons
  
• "kaching"--1,000 simoleons
  
• “rosebud”--1,000 simoleons
  
• “freerealestate”--As the name implies, all houses are free
  
• “Death.toggle”--Turn off death
  
• “resetSim ”--Resets the named Sim to a neutral state
  
• “testingcheats true” FOLLOWED BY “CAS.fulleditmode”--Allows the SHIFT + LEFT CLICK on sim “Modify in CAS” to enable the modification of traits, physical features, genetics, etc. Do NOT modify more than one sim at a time or your game will crash.
  

The Unofficial Cheats (The cheats TwistedMexican has kindly scoured the source code for; virtually all of these will require “testingcheats true” to be activated)

BUFFS

• “Sims.remove_all_buffs”--Removes all moodlets/emotions
  
• “Sims.add_buff ”--Adds a particular buff to the sim (spelling is very important)

Values for buffs:
sims.add_buff confidenthigh
OR
sims.add_buff e_buff_confident (This enables the cowplant essence effect, powerful and longer lasting)

Energized: EnergizedLow or EnergizedHigh (do not stack, high gives +2)
Flirty: FlirtyLow or FlirtyHigh (do not stack, high gives +2)
Inspired: InspiredLow or InspiredHigh (do not stack, high gives +2)
Focused: FocusedLow or FocusedHigh (do not stack, high gives +2)
Playful: PlayfulLow or PlayfulHigh (do not stack, high gives +2)
Sad: SadLow or SadHigh (do not stack, high gives +2)
Angry: Social_Angry, e_Buff_Angry, feelingangry, unfaithful (these all stack)
Happy: Social_Happy or e_Buff_Happy (these two stack)
Uncomfortable: e_buff_uncomfortable
Embarrassed: e_buff_embarrassed, peedself (these two stack)
***NOTE: e_buff is the same mood effect granted by cowplant essence, strong and lasts 12 hours

CAREERS AND SKILLS

• “Careers.promote ”--Promotes Sim in current career
  
• “Careers.demote ”--Demotes Sim in current career
  
• “Careers.add_career ”--Adds a career
  
• “Careers.remove_career ”--Removes a career
  
• "Careers.promote Gradeschool" --Raises child's grade performance by one letter grade
  
• "Careers.promote Highschool" --Raises a teenager's grade performance by one letter grade

Example: "testingcheats true" followed by "careers.promote secretagent" --Earns one promotion

• “Stats.set_skill_level 1-10” --Adjusts a sim’s skill level

Values for skills:
Major_Fishing
Major_Mischief
Major_Guitar
Major_Reaping?
Major_Programming
Major_Gardening
Major_GourmetCooking
Major_Comedy
Major_Charisma
Major_Writing
Major_VideoGaming
Major_Violin
Major_RocketScience
Major_Painting
Major_Piano
Major_Logic
Major_Handiness
Major_HomestyleCooking
Major_Bartending (Mixology)
Skill_Child_Social
Skill_Child_Motor
Skill_Child_Creativity
Skill_Fitness
Skill_Child_Mental
Note: Skilltypes are in two varieties. AdultMajor and Skill. Leaving the Adult off should still allow the command to execute.
EXAMPLES: “stats.set_skill_level AdultMajor_Programming 10” or “stats.set_skill_level Major_Programming 10”


MONEY AND ASPIRATIONS

• “Money ###”--Set’s funds to exact number
  
• “Sims.modify_funds +/-###” --Adds or subtracts value from current funds

Example: "Money 25000" or “Sims.modify_funds +500”

• “Aspirations.complete_current_milestone”--Completes current aspiration challenge and awards points (This one owns)
  
• sims.add_buff Satisfaction_Points--Adds 100 aspiration/satisfaction points. However, this applies as a buff and so, you will need clear with sims.remove_all_buffs before reapplying.

INFINITE CONSUMABLE ITEMS

• "objects.consumables_infinite_toggle" --Toggles the use of unlimited consumable items such as plates of food and aspiration rewards potions

Note: This cheat must be activated BEFORE you spawn/create/purchase the item. When using aspiration potions, the sim will continue to sip from the cup forever. In the case of eating plates of food, the sim will continue to eat the same plate of food forever. THIS CHEAT DOES NOT WORK WITH UPGRADE PARTS.


RELATIONSHIPS

• “Modifyrelationship YourSim(first name) YourSim(last name) TargetSim(first name) TargetSim(last name) (-)50 Track_type” --Modifies relationship between two sims
  Types of relationships (friends and romance): “Friendship_Main and Romance_Main”

Examples: “Modifyrelationship Beatrix Monroe Alexia Mercado -50 Friendship_Main” and “Modifyrelationship Beatrix Monroe Alexia Mercado 50 Romance_Main”

• "relationships.create_friends_for_sim" --Spawns a sim on your lot that has the "friend" status (50% friendship bar)
  
• "relationship.introduce_sim_to_all_others" --Makes your sim acquaintances with ALL sims still in the game, including deceased ones.

A NOTE FROM TWISTEDMEXICAN REGARDING RELATIONSHIP CHEATS
These may be used to counter several bugs, including the infamous mother-daughter/sister and father-son/brother bug in which an offspring becomes a sibling, and also a bug resulting in relationships persisting after death.
****A recent patch (09/09/2014) has been made to fix incorrect relationship states between sims.
WARNING: Some users have reported issues when using these relationship modifiers and then entering into build/buy mode or manage worlds mode. Testing is currently being done to confirm a correlation. Use at your own risk!

First we need SimID's...
Enter:

testingcheats true
sims.get_sim_id_by_name yoursimfirstname yoursimlastname

This command will print a number at the end, similar to: 775464154248314888

Make note of this number, it's your sim's unique id, I recommend making a copy somewhere if you'll be using these commands a lot.

Then run the command again for the other sim you're wishing you edit relationships for:

sims.get_sim_id_by_name targetsimfirstname targetsimlastname

Make note of this sim's ID as well.


Destroy a relationship:
Now we destroy the relationship (because were a horrible person;)):

relationship.destroy yoursimID targetsimID

Add Relationship Bit
(This lets you modify the type of relations between two sims. It also requires sim ID)

relationship.add_bit yoursimID targetsimID relationshipBit

NOTE: You can not REMOVE a bit, you'll have to override it with another. For example setting family_husband_wife will override family_brother_sister

The available family relationshipBits are as follows:

romantic-Married 
family_husband_wife
family_grandchild
family_son_daughter
family_brother_sister
family_grandparent
family_parent

TRAITS

• “traits.equip_trait ”--Equips a particular trait for your sim

Example: “traits.equip_trait SteelBladder”

• “traits.remove_trait ”--Removes a trait
  
• “traits.clear_traits”--Removes all traits from sim

Values for traits:
Lazy
MusicLover
Loner
Snob
Perfectionist
Cheerful
Goofball
Gloomy
piper
web_master
Savant
Collector
SuperGreenThumb
AlwaysWelcome
child
teen
youngAdult
adult
baby
elder
Childish
SelfAssured
Bro
Ambitious
HatesChildren
HotHeaded
Geek
Glutton
Evil
FamilyOriented
Clumsy
CommitmentIssues
Slob
Mean
Neat
Insane
Creative
FreeServices
Frugal
Marketable
SpeedReader
Observant
Memorable
Connections
NightOwl
MorningPerson
CreativeVisionary
Entrepreneurial
ProfessionalSlacker
EpicPoet
LivingVicariously
Outgoing
MentallyGifted
SociallyGifted
PhysicallyGifted
CreativelyGifted
Bookworm
Genius
ArtLover
Materialistic
LovesOutdoors
Good
ValuedCustomer
Invested
Piper
Chronicler
WebMaster
Sincere
Dastardly
Muser
Quick_Learner
Gregarious
High_Metabolism
Longevity
Business_Savvy
FamilySim
Legendary
SpeedCleaner
GreatKisser
Mentor
active
Romantic
Foodie
PerfectHost
Hilarious
Mastermind
Bane
TheKnack
NeverWeary
Independent
Antiseptic
HardlyHungry
AnglersTranquility
SteelBladder
GymRat
Shameless
Carefree
Fertile
Alluring
EternalBond
Player
Beguiling
EssenceOfFlavor
PotionMaster
FreshChef
Appraiser
OneWithNature
Expressionistic

SIMS, AGING, AND SERVICE ROLLS

• “Sims.Spawn”--Spawns sim and adds them to your household.
  
• “Sims.spawnsimple”--Spawns sim on lot as visitor without adding to household.
  
• “Setage”--Set’s your sim to adult age

Handyman: Enables an NPC to come to the lot and fix broken objects

Code:
soak.enable_soak_handyman_situation (execute this cheat first)
soak.create_soak_handyman_situation (execute this cheat after)

Maid: Enables an NPC to come to the lot and clean

Code:
soak.enable_soak_maid_situation (execute this cheat first)
soak.create_soak_maid_situation (execute this cheat after)

Party: Causes a ton of sims to show up for a party on your lot. They leave after a few sim hours have passed.

Code:
soak.enable_soak_party_situation (execute this cheat first)
soak.create_soak_party_situation (execute this cheat after)

Make your sim act like a maid!
They'll behave normally, do everything you tell them to as soon as you tell them, and do whatever they want when you aren't directing them. The difference? The second there's a puddle, a dirty plate, or trash to be taken out, they'll stop their own actions and go fix it.

Turn Maid Behavior on:
sims.add_buff buff_Role_ServiceNPC_Maid

Turn Maid Behavior off:
sims.remove_buff buff_Role_ServiceNPC_Maid


INDIVIDUAL MOTIVES

• "fillmotive motive_" --Fills a sim's individual motive such as hunger, energy, etc.

Example: "fillmotive motive_hunger" --Fills hunger


KILL YOUR SIMS!

• "sims.add_buff buff_death_electrocution_warning" --Equips a sim with a buff that will make him/her prone to dying while fixing an appliance; have the sim repair something electronic to trigger death
  
• "sims.add_buff buff_Mortified" --Equips a sim with the mortified moodlet/buff that will make him/her prone to dying from embarrassment
  
• "sims.add_buff buff_Enraged" --Equips a sim with the enraged moodlet/buff that will make him/her prone to dying from anger
  
• "sims.add_buff buff_Hysterical" --Equips a sim with the hysterical moodlet/buff that will make him/her prone to dying from hysteria
  
• "sims.add_buff hunger_Starving" --Pretty much a guaranteed death within 24 hours; sims will die of hunger
  

NOTE: Due to a bug in the game, any cheats that rely on "testingcheats true" to be active will need to be reapplied after traveling, entering CAS mode, reloading the game, managing households or town, or generally by taking any action resulting in the appearance of a loading screen.