I fairly frequently need to use an image editing application for random minor acts of vandalism (see links at left for examples), or just formatting and saving blog images.
I've had Paint.Net 1.1 RC1 installed for a while, but hadn't remembered to try it for anything.
Today I needed to edit text in a way MSPaint couldn't possibly accomplish, so fired PdN up to see what it could do.
Well, I'm sold. It's cool enough for me. It looks clean, it's intuitive, and it does layers.
If you're in the market for a no-cost Paint replacement that doesn't suck, give it a try! Download.