I know Maria and Venus design their on-court outfits, Serena also has her own designing company. Though I'm not sure if we should call Venus's designing ability a talent.
Petko plays guitar and drums. Vania King and Pavlyuchenkova obviously do some singing.
JJ is a certified drama queen.
If you are a former No1 and you look decent than you're a designer too Wouldn't call that a talent. Janković co-designed for one big fashion company in Serbia once
Ivanović reads books, is that a talent?