I could (CO-)DM as long as the world is freeform, and not a set adventure path. I'm just not sure if i would do a great job, since this would be my first try at it though.
I didn't have a particular setting in mind, so sure; the world can be freeform. So we have Matt and Sirix volunteering to DM? That would leave Cora and I as players, with maybe room for one more if there's any further interest.
I'm most familiar with DnD (3.5, 4 [can't say I'm overly fond of but I do know the system], and Pathfinder), RIFTS and a few others the best. I am, however, willing to learn and get other PDFs if needed.