Signing schedules can also be found on their website. If your local comic shop is not listed, give them a call for a complete list of events and signings. (And Comichron's John Jackson Miller will be at Galaxy Comics in downtown Stevens Point, Wis., from 1-3. Hope to see you there!)
You can read more about the origins of Free Comic Book Day — as well as its original purpose — here. There's also a handy FAQ page on the official website.