If you'd like to have your own pet's paw cast, you can order from the nice folks at Pets-Paws. The web address is http://www.pets-paws.com. Tracy and Eddie will craft a gorgeous keepsake for you at a very reasonable price. It's not just for dogs, either... they've got some cool photos on their site of other prints they've done. Be sure to scroll all the way to the bottom!
They can cast the paws in bronze, brass, copper or aluminum. They'll send you a kit to take your pet's paw impression (or you can make the "dough" yourself and send it... there's a recipe on the site), and when they get it back, they'll cast it in the metal of your choice. You can get an inscription on the back, and an optional hole for hanging. We had our dog's name engraved, which is probably what most people do. (Yes, we named him after hockey legend Hobey Baker.)
Maybe it's just me, but I think these pet paws some of the coolest bits of artistry available for purchase on tha interwebz!