When I was in England a few weeks ago, I asked Puffin Books if they'd be willing to send me some extra posters. As you can see above, they've made a very cool design which they give out to libraries.
Obviously, you can't find these posters in the States . . . until now. If you are a librarian or classroom teacher in the US or Canada and you'd like to receive a free signed UK Percy Jackson poster, send an email to the rickriordan.com website address. I will be picking one school's request at random each week between now and the release of The Last Olympian to receive a poster. This offer is only available to librarians and teachers, and you need to provide me with a verifiable school mailing address. Individual fans, sorry but I don't have that many posters! You can certainly ask your librarian to request one for the school, however.
Requests for posters must be received by April 15. The posters are pre-folded, and will be mailed in a standard document-sized manila envelope. Good luck!