There is a wide array of resources on the web about evolution, ranging from public access to technical papers available via PubMed to the excellent Understanding Evolution site operated by the University of California Museum of Paleontology and the National Center for Science Education. The grand daddy of them all, of course, is the TalkOrigins Archive.
Now a new resource has been established by T. Ryan Gregory, evolutionary biologist and blogger at Genemicron. It’s called Evolver Zone, and is “a resource for students, teachers, and researchers with an interest in evolution.”
Evolver Zone is a collection of a wide range of resources on evolution, from online databases to software to teaching resources to multimedia (including games!). I haven’t browsed the whole site yet, but what I’ve seen looks to be very useful, particularly for advanced high school and undergraduate classes. Gregory tells us the site is a work in progress, so check back often for new additions.