I'll try to find some links tomorrow since I can't remember the specific names of most of the skits. But some great ones include:
Entire Little Donny episode
Entire Thunderball episode
Ghost of a dead hockey player influencing an impressionable college student
The Poo Stick
Big Red Cat
That one with the cop looking for Bong Boy and screaming about his dead wife
From the same episode as Bong Boy, any time somebody looks in the bucket of truth
The Fortune COokie sketch
The kid that only says 'Shuh-up' getting slapped
The Jesus summer camp one where somebody won't confess to stealing the bugjuice
the one where dude has to make a pretty salad
I don't know, there's tons of UCB sketches that I like, I'm not sure what I'm trying to prove here as Ass Pennies is great and it's one of the more widely acknowledged ones.
I wish Comedy Central would put out season 2 and 3 on dvd.
Edit: just watched Ass Pennies again and it's still great. I guess it's just that that was one of the skits I saw the most, so maybe I started taking it for granted. The last 30 seconds or so are classic.