[iratsu]

One thing I would recommend looking at is Category theory. MarkCC has several blog posts about category theory at the Good Math Bad Math blog (http://scienceblogs.com/goodmath/goodmath/category_theory/, in general i would also recommend looking at MarkCC's other blog posts as a source of math inspiration).

Wikipedia also has a nice article about category theory. (http://en.wikipedia.org/wiki/Category_theory), and I will also recommend 2 books on the subject:

First is, of course, Category Theory for the Working Mathematician by Saunders Maclane. It is an excellent book, but I must also warn that it is not an easy book and probably requires a fair bit on mathematical maturity.

Second is Basic Category Theory for Computer Scientists by Benjamin Pierce. It is much more of an introductory book and provides many examples in Computer Science which are useful to those doing theoretical CS.