I just downloaded a new version of the GIMP, and realized there isn’t a lot of talk here about free and open source software per se, so here’s a thread
Here is a suite of software for a desktop publishing workflow:
GIMP is the Gnu Image Manipulation Program, a free alternative to Adobe Photoshop.
Inkscape is a vector-based drawing program, similar to Adobe Illustrator.
Scribus is for desktop publishing (brochures, posters, packaging, etc.).