One important concept that I came across was Opportunity Cost -- the notion of quantifying what you give up when you chose one option over another. I asked myself: Why am I rushing to pay off loans with 3% to 6% interest rates when the S&P has historically returned 11%?
This isn't quite the most sage advice. The opportunity cost of student loans is actually the interest that compounds over long periods of time. Making high student loan payments (as a large percent of your income) early on, and taking advantage of the maximum deductible portion of student loan interest can be smart. (http://www.irs.gov/taxtopics/tc456.html) But again, depends on how you "play" in the S&P.