First movie I ever saw him in was Lawn Dogs, a perfect little indie film from the early late 90s. He caught my attention by turning in a great understated performance and by taking off all his clothes... while looking like that. It was good. He's a talented young man.
I was a little surprised to discover that a young Mischa Barton is also in the movie, mostly since I didn't really remember anyone aside from a naked Sam Rockwell. There may have been dialog and a plot, I'm not real sure I remember those either.
Shortly thereafter he starred with one of my favorite actors, John Turturro, in the wonderful Box of Moonlight. Also much unclothed, but dammit, it's a good movie. Writer/director Tom DiCillo was something of a Sundance Film Festival darling, but BoM is the one that really caught my affections.
I've liked him a lot in a lot of other movies, but I will leave you with the trailer for one of my favorite under-appreciated SciFi movies of ever, EVER: Galaxy Quest. If you haven't seen it, you should. Despite the fact that Rockwell stays, pffff, clothed. Whatev.
Happy birthday dude! Rock on!