The US Department of Education has put together a portal linking to hundreds of federally supported free educational sites. Think of it as Merlot, but with a political objective. (i'm kidding. I joke). A couple of new sites I found:
The William Blake archive
Salem Witch Trials Document Archive
Middle English texts
the Animal Diversity Web
FBI Youth (good site that teaches a lot of forensics)
Be sure to check out the copyright teaching cyberbee who makes it fun to learn your sorely limited rights to use copyrighted materials - even for school projects! (click the girl on the bottom-left).
Thanks to my mom for sending me this site.