My favorite Free Software creative tools:

#1 at the moment is definitely Inkscape. A vector graphics program, it is super powerful under a very simple guise, and tons of fun!

#2 is Krita (my former #1). Beautiful raster painting creation.

#3 Libreoffice. We don't always think of it as a creative tool, but it is, I use it daily and it does what I need quite spectacularly.

#4 Zim is the perfect note taking and arrangement tool.

#fosscreative

@eladhen #fosscreative honorable mentions include Audacity, Musecore, Banshee (RIP), Nano ♥, Xed, and of course, standing in the background: Linux Mint, Ubuntu, Debian, Linux and countless upstreams.