No pets. We spent a couple weeks killing a few goldfish before we had kids. Our friends were understandably concerned when we announced our first pregnancy.
My daughter wants a dog, but my oldest son is deathly afraid of dogs right now. He claims to like "small" and "medium" dogs, but that's a load of hooie. Every single dog he sees sends him scampering off into the trees.
We may buy a fancy aquarium for my daughter for Christmas. She's said a pet would be her favorite gift. "Welcome to Paulie's Laboratory of Death, my little fishies!"