Very nice! I get so excited when I see other people on this forum to keep rats in things other than cat litter pans.

I think most people who keep rats for pets approve of giving them a variety of human foods (provided it's not junk foods).
I do something similiar to what you're doing for my pet rats, only I don't have the space in the fridge to keep their food in little dishes. I combine mostly leafy greens, veggies and some fruits and blend them into a slurry and then freeze it into small portions. I then defrost it in the morning and serve it to them over their morning oatmeal. I also give them some of whatever I'm eating for dinner that night, provided it's nothing on the 'forbidden food' list.

Don't know if you're on it or not, but www.goosemoose.com is a nice forum for pet rats.