I seem to always create sims with mainly skill-related traits: Natural Cook, Handy, Artist, etc. The last couple of days I've been experimenting with randomizing traits, practicing for the Random Wishmaster Challenge. One of the sims the game gave me has the Childish trait, and he wants to be a writer. Of course the household had no money, so he went to the library to start writing. But first I wanted to get his fun need up by reading. I found out that, unlike other adults, this sim could read the books in the children's section, so I had him read all of them - they're quite short. When he sat down to start writing, the message came up that he would be starting writing at level 3 because of all the books he read as a toddler! I haven't tried him with painting yet, but I expect he'll get a boost to that skill as well because of the books. Probably he could use the xylophone and the pegboard to raise his skills in those areas. The Guide says Childish sims can play with toys, but I don't think it mentions them using kiddie stuff to raise their skills - and it happened a lot faster than developing skills the usual way.
The other neat thing about him is that he can get everyone to play tag, which gives them all a lot of fun and social at no cost at all, and it's hilarious to watch. I may just have to start making Childish sims.
Anyone have interesting tidbits to share about other unusual traits?