What are good resources to self-teach mathematics?

Yes, this site as well as wolfram|alpha are both excellent resources for teaching yourself math!

In addition, I would suggest looking at this site. It provides tons of great math videos, if you are like me and too lazy to read your book sometimes. :) KhanAcademy is also good, but I do prefer the latter. If you can afford it, perhaps you should consider getting into an online class? That way you get more resources and a professor to directly speak to. Not to mention, most math jobs require that you show some accreditation (e.g. a degree). Not exactly sure about your situation, but thought I would mention it. Best of luck!