Here's an old thread about this topic:
http://greekchat.com/gcforums/showth...=famous+people
But to put my two cents in now...
I've met Scott Speedman, a.k.a. formerly Ben from Felicity, the band Lifehouse, and Nathan from Real World Seattle. During my internship, I had to hail a cab for Barbara Walters once, and I saw Leeza Gibbons at Venice Beach and stood next to Lauren Bacall at Farmer's Market in CA.
