Posemaniacs.com is one of the best sites I've come across in awhile.

If you are feeling down about your artwork and just uninspired, I HIGHLY suggest challenging yourself over there. Start off by just drawing what you see until you slowly get to a point where you just draw what you see, in your style.

It's a blast and really adds levels to your work. Turn and twist the models around to get different angles. Lots of fun and good practice.

Seriously. Try it out.