The Arm Triangle(aka Head and Arm Choke) is a great example of a technique that has evolved in recent years. Fighters like BJ Penn, and Thales Leites have successfully used this new version of the Arm Triangle a number of times in MMA matches to finish their opponents.

The major difference is that to finish the choke they use a gable grip as opposed to a rear naked choke grip. Another improvement is that they post the inside knee against the opponents hip. Check out BJ Penn, and Thales Leites applying the technique from a number of different set ups in the videos below.