Theres a free game where you think of an object and darth vader uses the force (and alot of questions) to guess what it is. You can find this game at:
www.sithsense.com
I thought about Mack super snow leopard geckos and after 24 questions he asked me if it was a gecko, I guess thats close enough...
Its pretty fun if your bored, and at times it gets kinda funny (this site is made by burger king, and occationally the burger king mascott will come out and talk to vader)
Next ill think about something crazy... Ill post the results
Let me know how good he is at guessing what you think of by posting the results of your game in this thread.