The man is at the top of his game in The Big Lebowski. That Babe Ruth movie was good too... can't really remember what else I've seen him in 
Try:
Roseanne [really... I'm serious]
One Night at McCool's
Any episode of Futurama where he plays robot Santa Claus [he's done a lot of voiceovers as Santa Claus]
The Emperor's New Groove
Beyond the Sea
and if you can find any videos of him on Broadway, watch them. He's one of my favourite actors of all time. IMDB him up sometime and read about him, he's such a cool person.
Also, look for him in Evan Almighty

Hey, I heard 'em. I heard their EP and it was freakin' good. It's like Michael Jackson reincarnated into a bunch of white kids on a disco run.
Not saying they're bad - haven't heard but one song - but Island Records' strategy is pretty transparent.
http://charlatantric.livejournal.com/86873.html You can download their EP here for free. This guy is the reason I've found so much awesome music this last year [and free, too!]. I also found Girl Talk thanks to him.
I'm off to disco, baby!