The Marx Brothers are great. My personal favorite movie was Horse Feathers, where they are at the college. His song on that "Whatever it is, I'm against it" was hilarious. And Groucho's lecture in the classroom with Chico and Harpo was also great.
Another great bit of theirs was the "crowded stateroom", where all those people were in the stateroom on the cruise ship. I forget what movie that was, through.

Anyone ever watch "You Bet Your Life" with Groucho? That was a good show. It was a game show, but most of it was Groucho interviewing the contestants to try to get them to "say the secret word". Of course wisecracks abounded. Several episodes can usually be found in the bargain DVD bin at Wal-Mart or some other like store.