I highly recommend a pet rat. I know, I know, rats are hated by most people. If you can get past the tail, which seems to be the most objectionable part of a rat, they make great pets. They are affectionate, smart, clean, they don't bite and are very gregarious. They are supposed to only live 3 or 4 years, but we had one that lived nearly 6 years and is still greatly missed. They are not much for home protection, but if you threw it at an intruder, it might scare them off! (jk)
I'm way behind here, but I loved the rat I had a couple of years back. One of the best pets I've owned! They are clean, and folks just don't think of that. They picture the street rat whenever they are mentioned.