Freely Available Web-Based Mathematics Reference?

HomeySmurf asks: "I am wondering if anyone is interested in a free mathematical reference document in hypertext similar to the now unavailable Eric Weisstein's World of Mathematics (Slashdot article about its demise here). I know that the body of this work was by Eric Weisstein, but the information itself is fundamentally open, and it is a horrible shame that there is not another similar document project in mathematics. Or at least I haven't been able to find one. Many of the math world submissions and corrections were by various knowledgeable individuals, much like an open source project. I know there is a GPL-like license for documentation, and that it could really come into use here. I would certainly like to be involved in such a project, and there are many different directions this could take." I remember reading about Mathworld when we talked about its demise. It would be interesting to see if a group of people could come up with something similar. Any volunteers?