First off there have been other poker movies mentioned in this thread already. Second if you want more its really not hard to find plenty more with a quick google search. Or 2+2 is usually a good spot for poker related things ... Here is just one guys list*
1. The Cincinnati Kid
2. California Split
3. Rounders
4. A big hand for the little lady
5. Dr. Mabuse : The Gambler
6. Maverick
7. Kaleidoscope
8. The Big Blind
9. High Roller: The Stu Ungar Story
10. The Grand
11. Five Card Stud
12. No Limit—Search for the American Dream on the Poker Tournament Trail
13. The Gambler (Kenny Rogers)
14. Shade
15. Lucky You
16. Havana
17. Freeze out
18. All in
19. Deal
Honorable mentions of films that had great poker scenes; but that were not based on poker overall : The Sting, Cool Hand Luke, Bob le Flambeur, Lock Stock and Two Smoking Barrels, House of Games, Oceans 11, Tombstone, Finders Fee, Run, My little Chickadee, Honeymoon in Vegas, McCabe and Mrs. Miller.
* Some guys All time ranking for poker movies on 2+2