
Screen Shot of Seashore Graphics Editor
There's actually quite a lot of free software out there, far more than I could possibly cover. So I'm just going to talk about a few applications that I know personally. I figure with any luck at all, a lot of suggestions will appear in the comments.
First up, a recent discovery for me; Seashore is a simple, easy to use and surprisingly full-featured image editor. It supports layers, channels, tools, including textures and brushes, and is perfect if you mostly want to do Save As from .png or .jpg or .tiff, including transparent .gif, and image scaling, by percentage or pixel. There's easy to use documentation embedded in the Help system. Read more