Some of the advantages:

Rats are friendly. Many small pets don't like being handled, but rats get used to careful socialization easily, and come to enjoy riding in pockets and on shoulders.

Rats are smart. Rats respond quickly to food-based training and seem to love learning and performing tricks.

Rats are agile and sturdy. Try to get a guinea pig to run a maze or climb a ladder, and you'll appreciate the fleet-footedness of a rat. Unlike mice, rats can stand up to the handling -- and occasionally, the unintentional mishandling -- of well-meaning children.

Rats are cute. Pet rats come in many colors and coat patterns. Think colors like silver mink, platinum, blue and chocolate, and markings like hooded (the head a different color than the body) or masked or patched.

Rats are easy to keep. All you need is a good-sized cage with bedding, a place for the animal to hide and sleep, a food dish, a water bottle, and some toys. Your rat will happily eat commercial food and will love to share your healthy food, too.

The downside of rats? They don't live all that long -- two to three years -- and they're prone to tumors. As with all small pets, cage changes must be frequent. Otherwise, the smell will become unpleasant, to you and your pets.