I have, and I think it's a great way of dealing with complicated joints. Here's what I currently have for the knee bend of my Antonia figure:

http://www.youtube.com/watch?v=bhq0s47--5U
http://www.youtube.com/watch?v=BBDS30dQxmQ

The idea is to use a series of JCMs instead of just one, each starting to take effect at a different angle. In particular, I would start to model the effect of the shin and calf being pressed onto each other at the correct angle at which this actually happens, but not earlier.

This is probably a well-known technique, but it is new to me, so I thought I'd share. If anyone's interested, I'm happy to explain in more detail what I did.

-- I'm not mad at you, just Westphalian.