I think it should either be drawing or painting... drawing would allow things like pencil, charcoal, pastels, colored pencil, crayons, pen & ink, etc. Painting would allow watercolor, oil, acrylic, poster paints
whatever. (if someone wanted to use ink in conjunction with any paints, that'd be ok too ^^)
I'd love to see what people came up with... someone doing really creative art & mixing media would just be awesome.