WisCon happens in Madison, Memorial Day Weekend, May 25-28, 2007. It's a hugely popular event and will fill. A brief description from their homepage:
"This is the world's leading feminist science fiction convention. WisCon encourages discussion and debate of ideas relating to feminism, gender, race and class. WisCon welcomes writers, editors and artists whose work explores these themes as well as their many fans. We have panel discussions, academic presentations, and readings as well as many other uncategorizable events. WisCon is primarily a book-oriented convention... with an irrepressible sense of humor."
For more info: www.wiscon.info