Khan Academy Math Videos This is an amazing free site that has literally thousands of instructional videos covering multiple content areas. If a certain mathematical concept is leaving you feeling confused, check here; odds are they have a video to help out.
Math.com Do you like math? Who doesn't! Here is a link to math.com, which as you can imagine is a site about math.
Cool Math This site is great because it doesn't make you wonder if it is cool or not; the name says it all.
Also, it looks like it was designed by a squirrel on a sugar high.
Math World A website designed by someone 10e1000 times better at math than me.