I do, about half of the times I use the MW. More often than not, just to heat liquid to a particular temp. It doesn't matter what temp the liquid is to start with, how much there is, or exactly what the liquid is--I just punch in the temp I want, and wait for the bell.
The wife still eats potatoes and popcorn, and those cook well in the MW. Of course you could argue that's not cooking, but rather just heating.
I'm actually having trouble thinking of any real cooking that I do in the MW--mostly just heating things up to a nice eating temp. I used to scramble eggs and cook them in the MW, but not anymore--it's just to rude to the fats in the yolks.