I study a lot of math in my free time, so I thought this would be a good place to post a few good resources I know of:
Khan Academy, as previously mentioned, is good. It's simple to understand, and he's got videos on everything up to partial differential equations, as far as I'm aware.
There is another site that is a university site, but the notes available are good, covers linear algebra, Calc one through three, and even differential equations. There are practice problems available for everything up to Calc I.
Wikibooks also covers many math topics, although the writing is typically not the most understandable, but a good resource none-the-less.
Wikipedia is good too, just for reference. I also have a few books I would recommend.
This is a good text, but requires that you know a good deal of algebra, and geometry.
Calculus: An Intuitive and Physical Approach
Another good book, although this starts from the bare minimum of mathematical knowledge. By bare minimum I mean addition.
The Calculus Direct: An intuitively Obvious Approach to a Basic Understanding of the Calculus for the Casual Observer
You may have noticed that I study Calculus the most, what can I say; I'm a sucker for change :p
Edit: How could I forget Donald Knuth? Another book for ya:
Concrete Mathematics: A Foundation for Computer Science