Maybe you didn't even know about BookTour.com, but I found it useful. I regularly listed my events there and also subscribed so that I would be alerted about listed events that were happening in my area. But now, as of September 1, it's going away, according to an email subscribers received yesterday from Kevin Smokler, the force behind BookTour, who also recently announced that he was becoming the VP of Marketing at Byliner, an interesting new publishing venture.
Supposedly there are alternatives to BookTour.com, including Eventful.com, but I really liked BookTour's focus. Best of luck to Kevin, et al.