Awkward Family Pet Photos is one of my favorite sites of that type. Mostly it's just funny, but I find it of research value as well. OK, so "research" may be pushing it a bit far. Still, I have a deep and abiding interest in the relationship between people and other animals. The idea of keeping pets is fairly unique to the human species.
I say "fairly" because there are cases of primates in research situations who adopt kittens. The tendency of cats or dogs to accept infants of the other species for fostering may be a similar phenomenon. As far as I know, these all take place in a human-created environment. That doesn't mean they don't "count", but it suggests that the domesticated environment may be necessary for such activities. Does anyone know of any "wild" animals that keep pets?