Here's my dirty microwave. One too many lasagna reheats left it in a mess. And in classic Sherrie fashion, I got distracted and didn't take an after picture. (It's clean - I promise!) Anyway, it occurred to me as I was cleaning it that you might not know the magic trick, so here it is: heat a cup or so of water (you can add a bit of lemon juice if you like) for 3-5 minutes on high. Let it sit there until you get around to taking it out. (Waiting at least a few minutes helps the magic to happen and keeps you from burning your hand.) The walls and ceiling inside will be wet from all of the steam, and you can wipe it completely clean in a few swipes of a clean cloth. Even the grungiest food goo comes off easily. Done!