I think he has been in well over 50 films, been in at least 5 TV shows (the deep end, samantha who, charmed, boston public, twin peaks) and at least that many movies made for tv. Big names - Titanic, Deep End, Tombstone, Orlando, Back to the Future (2 of them) - and directed Big Kiss (good luck getting a post facto viewing of this.
If you haven't seen I woke up early the day I died - and you have any appreciation for Ed Wood - Billy totally emulates Ed.
IMDB has a pretty extensive list - don't pay attention to the reviews. Lots of good actors have been in bad movies - Billy always adds something to the film and most comments reflect this fact.