Walking back to the microwave wouldn’t kill you
One thing the web is generally pretty good for is product reviews. People will try just about any product, and they aren’t afraid to post their opinion of it. Here’s a guy who dropped $16.95 on a little USB hotplate. As one of the commenters informs us, the power you can draw from a USB port is about 2.5 Watts. That’s enough for a little white LED reading light or an optical mouse, but that’s about it. Don’t forget to visit the product’s page in the catalog and notice the green LED they stuck in the USB plug!