Forgive me if this is off topic, but I've been looking for an online resource that I can use to polish up and improve my math skills. I've looked at math.com and purplemath.com but they don't have much past algebra. I want to know if there is a site that contains "complete" coursework for Trigonometry, Calculus, and possibly Statistics.
I believe Khan Academy is what you're looking for. As far as introductory mathematics university courses go, it has plenty of resources. Certainly it covers Trigonometry, Geometry and Calculus well enough.
You might also consider MSE for lots of problems (but perhaps most harder than what you are looking for). Look at the relevant tags. Search for math olympiad preparation material, and for problems and solutions in such. Again, probably much harder than what you are interested in for a first look,