I think this topic has already been made, but I won't say anything.
Anyway, my fav is Dogma just because I like it when a movie comes out that makes fun of the Catholic church (BTW I am a Catholic). Plus if you have a chance to see the special edition DVD the commentary track is gold!
My second fave is Jay & Silent Bob Strike Back......funny as hell!
I also like the Clerks Cartoon DVD which was left off of the list. Pick that up if you loved Clerks......or any of the Askew movies.