My favorite is the backwards episode, but I am also partial to any episode with Peterman.
Me too.
He has some classic one liners.
During the Rachel(sp?) Welch episode and Elaine tells Peterman that her co-worker (the one that doesn't swing her arms, Molly Shannon), is stalking her, Peterman says:
"Looks like I'm smack dab in the middle of a good old fashion cat fight."