The FAA has a search interface where you can find out what certifications various pilots have.
I just looked up George Walker Bush, he has commercial certificate for single engine, multi-engine, and instrument rating. He got his initial certificate in 1969.
His dad got HIS certificate in 1945 (Commercial Pilot) but is only single engine. No instrument, no multi. Thought that was pretty funny. Wonder if that ever comes up at BBQs.
John Travolta's certificate, interestingly enough, is only Private. He has instrument, ASEL and AMEL plus type ratings for P/CE-500, P/G-1159, P/HS-125, P/LR-JET, and VFR limits for CE-500.
I'm finally listed, takes the system forever to update, but a cool resource.
http://registry.faa.gov/amquery.asp