What a great way to collect $$ to support shelters. I wish we had something similar here in Canada - it seems we are always just putting the Queen of England (no snub to her, though) on our stamps. I just wish we got a little more creative with our stamps.
Our postal service spend a lot of $$ on new stamps, because they know some folks will collect them and never use the, just put them in books.
But this does help the animals..so, please, when you need new stamps, ask for these.