Well, rats are quite intelligent and I'm sure if I could get the daughter over the squeamish portion of having a "rat", we'd have those crawling about as well!
But, unfortunately we have out hamsters. I do have to admit this time around on the hamsters since I hadn't had one since a small child, that it's alot more easier than I expected.
Has anyone tried to litter train their pet mice/rats? I'm interested to know. Trust me when I say that it helps on the clean up tremendously if your pet will do this. It cuts back on the constant cleaning of the shavings. I'm not sure about everyone else's pet, but my hamsters are quite upset after a shaving change. Even with leaving their sleeping area alone.
Heck, I think all my pets are sensitive to move type changes. My oscar goes completely off the wall when I move any thing around his tank!
Edit: I should add that I mean everything including inside and outside of the tank can't be distrubed without the corner balling behavior. Meaning don't move that table... or that vase.. or anything