I like the fact I can go here to find virtually any picture. That's a fantastic resource- you're to be commended!

The navigation needs work. Scrolling to the bottom of the page for an enlarged thumbnail is tedious, at best. Folks aren't going to read your blurb with viewing instructions (indeed, you probably shouldn't need instructions). With some shuffling of the layout, getting everything within a standard viewable window should be doable. This will make the site intuitive enough to use, will eliminate a rather baffling page load (when you click a thumbnail at the top, the page reloads, and you see no difference until you scroll down), and make the pictures more directly viewable.