I Am Sam - An autistic man who joins fatherhood and raises his daughter on his own. This movie I discovered through a movie list including movies with Beatle references, and this had plenty of that and only used (very very nice) covers of Beatle songs throughout the movie, it's an awesome use of Beatles history and music that fits the story very well.
Mozart And The Whale - This I haven't seen entirely, but the start of the movie was really good. From what I understood it's a movie about a couple falling in love, both having Asperger Syndrom, they're not "the same" as each other and that makes the story work a lot better and make it more interesting.
If anyone knows any other movies like this, please post.
Enjoy.

List of movies mentioned so far
I Am Sam
Mozart And The Whale
Mercury Rising
Search Of Bobby Fischer
Cube
Adam
The Waterboy (Not really autism, but includes some kind of mental "disability")
Rainman
Marathon
Hellraiser2
What's Eating Gilbert Grape