The site looks great. It's very clean, which I love.

One of the things I would do is split the main page into left and right and move the "Recent Artwork" to the right of bullet point list on the left. This will let prospective users see artwork right away and you don't really lose anything since there isn't much content in the bullet points anyway.

Also, I would lose the captcha for the signup until you have a spam user signup problem. No point in giving people another obstacle to signup if you don't have to. I would lose the "password again" field also as I've never really liked it.

Good luck.