I'm not in favor of wrist lock myself because my opponent still has too much freedom on his elbow joint, but I'm in favor of elbow lock, shoulder lock, waist (spine) lock, knee lock, ankle lock, and head lock.
I have used this elbow lock so many times on the mat. It's one of the 1st degree black belt testing requirement in ACSCA. One of my guys had shown this "elbow lock" in his Sambo/Judo club (all my guys have cross training) and those Sambo and Judo guys all loved it.
http://img691.imageshack.us/img691/1032/cracking.jpg