I'm sure this has been done, but I thought I'd do an updated version.
Everyone knows the old schoolers:
Harrison Ford
Bob Barker
Al Michaels
James Dean (yes, I realize he never was initiated)
But here are some that I only recently learned were Snakes:
Paul Rudd (Nu / Kansas) - Best known from Anchorman, The 40 Year Old Virgin, and Clueless.
Brian Fantana: No, she gets a special cologne... It's called Sex Panther by Odeon. It's illegal in nine countries... Yep, it's made with bits of real panther, so you know it's good.
Josh Saviano (Beta Alpha / Yale) - Paul Pfeiffer from Wonder years!
William Daniels (Gamma Beta / Northwestern) - They main teacher guy from Boy Meets World (also the voice of Kitt in Night Rider).
Joe Buck (Beta Eta / Indiana) - Fox Sports. Google him, you'll recognize him.
Eli Manning (Epsilon Xi / Ol' Miss) - Giants...
Chip Arndt - Amazing Race 4 Winner. Best known as being the ex-husband of Reichen Lehmkuhl (who is the dude that Lance Bass came outta the closet with).