For those of you that enjoy leg locks, Masaku Imanari is a fighter you need to know. I've seen him complete more leg locks in MMA than any other fighter. Here's a good example of what he likes to do in MMA. Check out his fight against George Gurgel. You might want to forward the video to the beginning of the fight at 1:18.
Here's another nice leg lock (heel hook) in a fight against Jean Silva at Elite XC
Masakazu Imanari is known as a leg lock specialist, but that's not all he can do. Check out this nice finish in his fight against Robbie Olivier in a title fight at Cage Rage 20.