Wow Brendan, you have talent! I like your artwork...
I have a couple of small suggestions to make. I think that a website to show artwork should be minimalistic, so the attention stays with the art. With that in mind, I'd go for an all-white background (lose the grey and yellow areas).
Your logo needs to be consistent (its red and black at the top, and all white in the main image). As a logo it's also a little plain.... if there is one thing on your minimalistic site that is allowed to draw attention - it's the logo! Because this is another way people will remember you by.
My only other suggestions is to left-align your text on your About Me page, as it looks a bit unusual being centered.
Aside from that, I like your easy navigation and how you can access any image from a thumbnail on every page. Good work!