Base game:
While a Sim is pregnant, that Sim as well as the spouse (if there is one) will have wishes to buy baby/toddler objects.
Even if you turn off story progression, premade pregnant Sims will still give birth. But the baby won't age unless aging is on.
If two Sims with a romantic relationship are cuddling on a bed (choose this option first!!) then there will be another option to kiss the other Sim. First kisses can be done in bed this way.
Into the Future:
Plumbots have a special lifetime reward that's supposed to remove the maintenance need. If it works? I don't know, haven't tried it out yet.
If a Plumbot adopts a child, then the Plumbot's creator will count as the grandparent of that child.
Plumbots (even if built in the present and you've never been to the future before) are treated as if they had level 10 in the future technology skill, even though it doesn't show under certain circumstances. If they have the repairman trait chip they can also instantly upgrade the sonic shower even if your own Sim has a low technology level.
The same goes for children that were adopted in the future, but the skill always shows.
A Plumbot with the learning trait chip installed can actually learn the bot-building skill. Which means that this one Plumbot could build an army and take over the world. Or something like that.
Plumbots can make silly faces. Don't ask me how.
The current emotion of a Plumbot (happiness, sadness, anger, flirtiness) is shown by a symbol on its display. The graphic varies from head to head, where the less advanced looking heads have more pixelated symbols.
In the dystopian future, meteors fall down pretty much every day. But did you know you could actually collect those? They're sometimes pretty large things that literally won't fit on anything but the floor.
For the creation of a dystopian future you will receive a meteor magnet. And you can keep it! I often had my Sim get wishes and autonomous actions related to attracting meteors too.
If you look closely at the "screwdriver" they use to tune Plumbots, you'll notice how it somewhat resembles the Sonic Screwdriver from Doctor Who.