Saw a "best of..." reel, but it didn't seem all that great cause it was mostly just Tom Kenny. Now, I think Tom Kenny is hilarious, but I think a highlight reel should have a diverse collection of material. If you didn't know, Tom Kenny was a cast member on Mr. Show, and is also the voice of Spongebob Squarepants.
Anyway, this is a clip of Mitch Hedberg on Dr. Katz.
EDIT: Special note, I actually posted this video on my blog the day before it hit Digg. Woot.