The people I've asked so far would only be doing ink or pencil. I'm interested in comic books and cartooning. I am specifically after work that results in a physical piece of artwork, but otherwise medium isn't a big deal.
I wouldn't necessarily expect anyone to do a painting, though. I am asking for originals and I can't afford to pay (the offer of my drawing 'subject of choice' in return is open to those who find my questionable artistry of some value), so I'm not expecting masterworks. The original motivation was creating an interesting display for one of my walls! But I won't rule out something more public if what I get turns into something with a wider appeal*. I don't know if anyone on here is artistically inclined, but I do welcome contributions from anyone as long as it isn't stick figures or whatever.
(*If I did put it out as a small press booklet--subject to contributors' permission--the run would be something like 200 copies, digest-size. I can predict that based on my lack of a real budget! Obviously, I'd give it a plug here for those who might be interested.)