Today, Town Hall becomes a mecca for popular fiction: Downstairs, Eva Gabrielsson reads from her memoir about life with Millennium Trilogy author Stieg Larsson. Even crazier: Upstairs, Neil Gaiman celebrates the 10-year anniversary of what is arguably his best loved novel, American Gods. From his comics to his fiction to his recent Doctor Who episode, Gaiman has enchanted geek audiences for almost a quarter century now. He'll read and then talk with local fantasy author Maria Dahvana Headley about magic, writing about magic, and being magical. It doesn't get more splendidly nerdy than this. (Town Hall, 1119 Eighth Ave, 634-3400, 7 pm, $5)