I remember looking at this Khan Academy some time ago, but just went out and looked at it again. It's a HUGE series of very short tutorials on topics ranging from basic algebra to physics to astronomy to history. . .with some practical information about the current credit crisis, currency, and economics. I discovered that you can actually assign work to your students and then follow what they complete on this site. If you haven't looked at it lately, check it out! I might go back and try to re-learn algebra!
This is particularly interesting in light of the OER project. Sal Kahn has created 1000+ free videos, and he notes that he hopes to add 200+ a year and eventually have "the history of the world" out there!
Check it out at The Kahn Academy.