MovieTickets.com just did a poll of the greatest Best Picture upset in Academy Awards history:

1. Shakespeare in Love over Saving Private Ryan (44%)
2. Crash over Brokeback Mountain (18%)
3. Dances with Wolves over Goodfellas (13%)
4. Rocky over Taxi Driver (13%)
5. How Green Was My Valley over Citizen Kane (12%)
Total Votes on MovieTickets.com: 4,836