Celebrate pet birthdays?

I've never celebrated a pet's birthday, but there's some really great ideas here! I picked up my cats directly from the street, so I don't know their birth dates, I have calculated them approximately based on their age when I found them (they were both about a month old). Some people celebrate their pets birthday by making cake and other human treats, that just seems a bit silly to me. I really like the idea about wrapping the presents, my cats would really like to play with the wrappers and the boxes. I would probably buy them some new toys and treats. As a birthday snack, they could get their favorite wet food, maybe some homemade snacks... Maybe even some human food they wouldn't get normally I would really like to see my cats with little birthday hats, but they would never allow it... There are some really great ideas out there