There's also the arts and crafts table from the base game, which Seasons added a lot of craft options to. Also I only recently realized there are potion options that unlock at level 10 of the mental skill for that chemistry set. I always used it to raise the skill and then stopped when I had it maxed, but apparently you can add things to emotion potions to align them to specific emotions.
They can use the base game observatory also. And the various dollhouses and individual toys. Some of the toys talk. They can play with and feed a full grown cowplant. They can have a journal, and with Parenthood that will affect Emotional Control.
With GT they can dance, and will do it pretty much all the time if you have a radio in the house.
If you have Vampires they can play the pipe organ.
C&D: They can't walk pets, but they can play with them and they have some very cute hug animations. Feeding them also raises responsibility if you have Parenthood. I don't know if they can train them at all, but they can play fetch with a dog who has been trained, I'm pretty sure.
With Jungle Adventure they can excavate, even though I don't think they can use the table to authenticate what they find. They can go through the jungle but there's not a lot that's fun for them and it's kind of dangerous.
They can bowl, with bowling stuff.
They can interact with the little pets in My First Pet Stuff.
They seem to enjoy the chocolate fountain from Luxury Party stuff.
I believe I read that they can play in the vanity from Vintage Glamor stuff but I keep forgetting to try it.
@ChuChuExpress I did have the thought when I was writing up that last post that maybe I had seen pictures of Roddy doing karaoke, but I wasn't 100% sure. I know I've seen pics of him recording videos with the video station - is that something that kids can do with Get Famous or do you have a mod for that?