I know some authors have set up signings at places other than bookstores, usually a type of store or coffee shop mentioned in their book. Some of those nontraditional settings (bait shop, beauty parlor, toy shop) work out well, especially with good publicity beforehand.
Book fairs and author fests appeal to readers and can be a good venue for authors. The biggest I know of is Printers Row in downtown Chicago. In 2002 this was renamed Printers Row Lit Fest and run by the Chicago Tribune. It takes up five city blocks - down the center of Dearborn Street from Congress to Polk - in what used to be Chicago's bookmaking neighborhood. I shared a table there with several other authors from my publisher in 2003. It was fantastic to see all those readers filling the streets looking for books. Another large gathering of readers and authors is the Twin Cities Book Festival on the Minnesota State Fairgrounds.
Smaller author fests I've participated in have been set up at craft fairs, at college campuses, resorts, even in shopping malls. Success in terms of sales can depend on so many factors: publicity, the mix of genres by the authors, table spacing, what events are elsewhere in town that day, and, most importantly, the weather.
Science fiction and fantasy conventions are good places for readers and authors to meet. Some conventions will often offer their participating authors a signing time. If the signing tables are near main programming or the dealers room, signings will go well for the authors. Some conventions, though, have the signings off on another floor, which means only the dedicated fans will go looking. When you're an author with a small press, you need your books to be visible for impulse buyers as well as fans.
How have your book signings gone? Do you have any book fairs to suggest?