Mr. Khan's videos are pretty uniform, and his teaching style isn't for everyone (think "electronic whiteboard"). But if you like diagrams and narrated explanations, you can't go wrong here. He has EIGHTY algebra videos (and that's not including his "worked examples"), thirty on geometry, and about a million on pre-algebra and preparatory mathematics, if you're weak on your fundamentals. Oh, and while you're at the site, you can also learn about economics, finance, astronomy, chemistry, history, physics, and biology. Hey, why not? Check it out for yourself:
http://www.khanacademy.org
BONUS! Did I mention that he worked through every math problem in the 11th edition of "The Official Guide for GMAT Review"? If you have it (or the 12th edition; they changed only a small part of the math section), you can "check your work" here, and have the tough problems explained to you. One caveat, however: he doesn't always find the most efficient path to a solution, so sometimes he takes longer than you should on the test. Overall, though, a great resource!
http://www.khanacademy.org/