Obligatory disclaimer: As pets, rats are actually much friendlier, smarter, and more social than most other rodents! They're practically the dogs of the caged pet universe. They really don't deserve their unfortunate rep... not even as plague carriers. (It was fleas that carried it. The plague was actually as fatal to the rats as it was to humans.)
So there, I said it. Rats get the raw deal. Angry emails from passionate rat owners... totally dodged!