Thanks to Doug Napoleone, PyCon's online schedule application is now online. Picking among all the amazing possibilities at PyCon is incredibly hard, but the online scheduler at least helps you keep track of what you've decided. If you get confused, scheduler help is here.
You can (and should) also use the scheduler to volunteer as session staff! Session staffing is an easy but important job that helps the conference runs smoothly, lets you meet the speakers you're most interested in, and gives you that open-sourcey pride of ownership in your PyCon.