Some of you that follow me know I don't try to jam the O-lifts down peoples throat but done correctly the hang snatch (or clean) is surely an easy way to self monitor and increase RFD and strength speed specific to the VJ over time:
http://www.scribd.com/doc/236664/Canavan-et-al-1996-Kinematic-and-Kinetic-relationships-between-an-olympic-style-lift-and-the-vertical-jumpA friend of mine did some research on a masters thesis several years back and the high hang snatch actually came out ahead of the depth jump and loaded jump squat as far as EMG specifity to the VJ.
I like the hang versions of the snatch and clean. Not that they're necessary, but they're relatively easy to learn, easy to implement, and also provide a great potentiation exercise. The best thing about them compared to a jump squat is they're much easier (and I think funner) to monitor than a jump squat because the weight's either getting heavier or it's not...you have something more tangible to shoot for. They also help sports specific upper body strength as it relates to rebounding and such. I like to have people alternate a set of O lifts with a set of plyometric variation like depth jumps, tuck jumps, etc.
Want a simple formula to shoot for as it relates to gains on the lifts for overall athletic success? Add your bench press, midstance legal squat, hang snatch, and hang clean together then divide by your bodyweight. The number to shoot for is 6. If you can hit that chances are you're gonna be one explosive m'fer. I learned that formula from a throwers coach years ago. His wife IIRC was a bobsled competitor and former college basketball player. Acording to my notes here he said that in college basketball she ran her butt off for 4 years and ran a 5.1 40 at 208lbs when she left basketball. Two years of weight training later she weighed 212 and ran a 4.7 and improved her vertical 6 inches without running or jumping in training.
In 1985 her bodyweight to strength ratio on the 4 lifts was just below 3.00. In 1987 it rose to 5.33 and she became a different athlete.
I had a guy a few years back really dedicate himself to that formula after I discussed it with him. His main focus was getting bigger and more muscular the explosive gains were secondary. I trained him for a while and got him started and he kinda took things on his own with occassional input from me and over a span of a couple of years went from 155 to 190 lbs and increased his vert from the mid 20's up to 39 inches and all he really did was throw in some depth jumps occassionally.