I'm considering doing one of these online workshop's being run by one of my fave photographers Sheye Rosemeyer. Seh has a fantastic, quirky style and gorgeous processing. Be sure to check out her blog.
I think I'll end up doing the Evolve workshop - I'd prefer to feel a little out of my depth and challenge myself rather than go over stuff I have already picked up (hopefully).
I found the SLR course I did at a Camera Club earlier in the year useful but wasn't as specific to my interest as this online workshop should be. I also learn much better in a self paced kind of environment rather than a classroom style environment.