As much as I don't really think we need a Graphics Showcase Moderator, I believe you'd probably be the only appropriate choice for the section. You're quite active in the section with your signatures, etc. Also you're active on the forums and I do see you helping out quite a lot.

For GD, I think you'd be a relatively good choice for the position as you're quite active in the section and you're helping out regularly.

No negatives really, good luck, I think you're a good choice in either of the sections.