I can do pretty much all of the things for a game, but I have been working and learning solo for so long.  I would benefit a LOT from learning to work with a team again.  It's been a lot of years since I've done that.  I know a guy for music, but I think at least one artist and one or two other in-engine coders/builders would be good to have.  I can helm design, or I can focus on systems/effects/you name it.
I've also never actually done a game jam before and I really want to try so I can bring that experience back to my own projects!