Yay! It's time for our collaboration with What is it? blog: can you guess what this strange hammer is for?
Place your guess in the comment section. One guess per comment, but you can enter as many times as you'd like. Please post no URL, so others can play, too. You're playing for a Free Neatorama T-Shirt. More clues at What is it? blog.
Good luck!
Update 4/11/08 - the answer is:A banker's check canceling hammer, used to mark checks after they've been cashed.ad who won the Free T-shirt!
Congrats to ad, who got it right first: it's a banker's hammer to mark canceled checks.