This article in today's edition of The Seattle Times was sure interesting, I thought. And certainly helps answer that old "When are we ever going to use this?" question.
My wonderful sister-in-law found a couple of good links for me recently. This one has to do with the Riemann Hypothesis, while this one is a musical tribute to π. Oh, yeah, and here's a site about number spirals.
And finally, free graph paper as PDF files!