PreCalc

[AzonicZeniths]

Probably one of the best sites to learn PreCalc on:
http://www.math.ucdavis.edu/~marx/precalculus.html
I also have this one, but its not as good:
http://www.themathpage.com/aPreCalc/precalculus.htm

[chasely]

+1 for these sites. They are really helping me study for my math placement test.

[physicsnoob93]

Another one is one by a guy from lamar.

The website is tutorial.math.lamar.edu i think.