Twinkle Toes: A Sim with Twinkle Toes gets a great moodlet from dancing, gives a great moodlet to anyone with whom s/he dances and gains athletic points from dancing for prolonged periods.
Happy Feet: A Sim with Happy Feet makes the best nectar.
Kid-Friendly: For Daycare or Teachers or anyone who interacts with kids. (EA would have to be careful with this one for the sake of ratings)
Methodical: Methodical Sims will always plan and plot before leaping into action. Especially good for Science or Law Enforcement.
Laid Back: Ahhhh. It takes a lot to ruffle the feathers of the Laid Back Sim. Regardless how chaotic the circumstances, "it's all good".
And I'd like to see more traits that span several areas. Artistic and Perfectionist should both have an impact on Photography, for example or Disciplined should have an impact on Athletics, not just Martial Arts.