The Mathematical Association of America (MAA) will host a national conference on August 2-4, 2012, in Madison, Wisconsin. It seems it is a big event that I had not been aware of; the website mentions that 1, 535 participants were present last year.
While the registration price seems to be exorbitant for institutions, I would say the Graduate Student price is rather reasonable ($50). Also, discounts are offered for reservations at the Hilton Madison Hotel and Sheraton Madison Hotel; for a cheaper price, the Madison Smith Hall at the UW-Madison has available rooms for the conference.
Furthermore, the invited addresses seem to be interesting, and graduate students will definitely find many ways to keep themselves busy with all the activities for graduate students.
Take a look. I hope to see some of you over there.