|GNU Image Manipulation|
Program (AKA: GIMP)
Despite the awful acronym, The Gnu Image Manipulation Program is a decent image editing program—a free alternative to something like Adobe's PhotoShop (which is awful SAAS now). Another (Windows-only) alternative that's popular is Paint.NET. And the drawing tool Krita has a lot of feature overlap.
Recently a project/fork of GNU IMP based round fixing the name and improving the program generally. Currently it's called Glimpse, but that may change. You can find out more at glimpse-editor.org. At the moment you have to compile it yourself, but that'll change soon! (If you use Arch Linux there's already a package in the AUR)
Gnu IMP can already create animated GIFs (each layer becomes a frame), but there are some tools to make the process easier.
GIMP Animation Package
- Using GAP guide.