I visited with Sara Archer, Executive Director of the BMHS, and met their newest unique pet up for adoption. Bro is a 1-year-old rat with a very sweet temperament who loves to be held. He comes with a large mansion-like enclosure. It is probably the best enclosure I've seen for a rat.
Rats make fantastic pets. For more info on their care: http://www.aspca.org/pet-care/small-pet-care/rat-care