Here is a cool omaplata variation. This variation does not require you to perform the traditional sit out, but instead your foot goes under his chest to secure the submission.

This gi choke works but here are some pointers to make this choke work. Once you wrap the guys arm, utilize the knee on belly along with your hand closest to the wrapped arm and release the pressure on the gi wrapping his arm. If you don’t release the pressure on the wrapped arm, it’s almost impossible to pass your arm under your opponents gi to secure the cross choke.

Hugo has some great gi chokes, this is in French, but you can get the idea from the video.