Yesterday morning, Neil Gaiman made this announcement on Twitter: "NEW YORK! There will be a ninja book signing at St Mark's bookstore on 3rd Ave & St Mark's. From 11 to 11:30am today. I'll bring a pen." One of the many fans who showed up already had his signature: as a tattoo on her arm. After the event, he tweeted: "The @stmarksbookshop now has LOTS of signed books by me. Perfect holiday gifts for people who like my books. Useless for anyone who doesn't."