The main image at the top, in my opinion, is far too large. Though it is "neat," and rather intriguing, I think half the size would be better. I am using a somewhat higher resolution than most people generally use, and the image still takes up a good portion of the site's real estate. Content-concentric is always the best way to go...focus on the content of the site, because that is what the people are there for.
Edit: It would also be rather interesting if the top image changed from page-to-page.
But overall -- I do like the design, layout, and color scheme. Well done.