A word of advice to those of you shopping for pet-lovers: pretend that they do not in fact love pets. Pretend that they do not own pets; pretend that they do not know what pets are. These people whom you love and care about enough to shop for them, they have other interests. They also have mothers who buy them gear with cats on it eeeeeevery yeeeeeear. So: consult their Amazon wishlists. Ask them what kind of movies or colognes they like. And unless they ask specifically for pet-related presents, don't go there. (Or stick to a gift certificate.)
Otherwise, you risk ending up on the internet, the object of a scathing slideshow full of kitten sweatshirts -- and gosh darn it, you're better than that.
And if you insist on buying a petsy gift? Please don't make it one of these. Please.