I know a lot will want to name recent ones like Will Ferrell in 'Wedding Crashers', or Tom Cruise in 'Goldmember' - but for me, I gotta go back a few years.

A near forgotten Dudley Moore flick called 'Wholly Moses' (1980). It's a pretty funny Biblical farce, but the 4 minutes on screen of John Ritter playing the Devil is absolutely brilliant.

Any others?

Steve Vai as the devils champion in Crossroads..(does that count)

I think the cameo that lance armstrong had (he's a terrible actor) in Dodgeball was pretty good

I'll try and come up with some more

Sly Stallone in Stay Alive...

The Big Question: Why?

I think Sly in Staying Alive was pulling an Alfred Hitchcock by appearing briefly in his own movie.

Stephen King as the pizza guy in 'Rose Red' [kinda a schlock mini series but that was a cool moment.]

Ralph Bellamy and Don Ameche as the homeless guys in 'Coming to America'[reference to Trading Places].

And, not exactly a cameo but did anyone ever see Bill Cosby play the Devil in "The Devil and Max Devlin"? It's a typical Disney flick and you really have to clean up the sugary goo that has poured out of your TV all over the floor after watching it, but Bill as a bad guy is unexpectly good. I wish he'd do more like that.

"Steve Vai as the devils champion in Crossroads..(does that count)"

Hell yes. That was a cool cameo. I love that movie. Not because the movie is all that great, but because of the lesson it teaches. Not that most people got the lesson. Hint: It's not a lesson like a parable.