Funnest math games I've found (and other learning games, too)

I'm doing a lot of searching out of math games for my kids to practice their math facts. Worksheets just don't cut it for them--too boring--and MOST math "games" are simply worksheets where you can only see only problem at a time, sometimes with a cute frame, and sometimes with cute animation. But it doesn't really qualify as a game unless there is a progression of some kind and a way to win.

This site is my favorite so far: http://www.fun4thebrain.com/index.html

They have other learning games as well (language arts, reading, science) and animated tutorials. I just haven't played those yet.