most of the collab tools for drawing that I've seen so far cost too much, and lack features. GIMP does everything that I want, but unfortunately I don't know of a way to draw with 2 or more people over the internet. is there a plugin that will accomplish this?
Verse used to be the solution. I knew several teams that used it, but it seems as if the project has been discontinued. Several people in the GIMP community have talked about resurrecting Verse, or making another collaborative process work out, but I don't think that ever panned out.
Good luck finding something. Let us know how it worked out.
The GIMP Plugin Registry is probably a good place to start: http://registry.gimp.org/node/25966