Crowning Moment Of Awesome: If you played the games, you'll cheer every time Dastan pulls a stunt lifted from them (there's even a brief wall run). They also managed to make such stunts look not too unrealistic most of the time.
Seso's knife-fight (which has been described as a "gunfight with knives") with the Hassansin in the Dagger of Time's chamber is probably the most widely-agreed-upon CMOA for the movie.
Most of the one-on-one duels in the 2008 game will have The Prince just utterly overpowering his opponents at some point in the fight. Keep in mind that these are all dark-empowered mystic beings that are much larger than the Prince himself. One of the better ones involves the Prince headbutting the Mourning King into submission. The Mourning King is a seven foot tall fully and heavily armored knight with an especially ornate and imposing helmet.