March 4 - Participate in silent auctions. Don't just donate a signed book -- put something related to your book with it. For example, when we donate the collection of books for a former war correspondent, we partner with a local restaurant and make the auction item "Lunch for two with John Hlavacek" or for our Las Vegas Mafia expert we call it "Cocktails and Mob Stories for you and three friends with Steve Fischer." It's worth more to the auction if it is not just a bunch of books, and it gets your name out there with a little mystique.
Watch for events everywhere (should be 4-8 weeks away so you can be in the program), and do deliberate searches too. Google the words "Silent Auction" along with the topic, town and a month at least 1-4 months away. For example, my search today was "silent auction" teachers Orlando May 2011. Weed through your results, and you'll find ads for events that include silent auctions. Simply email the coordinator listed on their event information with your auction item, a snappy description and a value.
Yes, it's a little work, but lots of people will see your book during the auction, it will be in the program for the event as an auction item, you can tell your story to the winner AND you are helping a cause. Take pictures and post them on your social media sites. Remember though, the buyer is looking to be entertained, not bored to tears! (Oh yeah, your donation is tax deductible!)