I've been using open source software for my artwork for just over a year now. Here's some of my work so far, hopefully it'll inspire others to get creative!
Vacuum Packed Children by hellocatfood, on Flickr
Made using a combination of Inkscape, Imagemagick and GIMP and Sed
I Am Sitting In A Room by hellocatfood, on Flickr
A still from a video made using a bit of C, Font Forge, Inkscape and ffmpeg. Full video is here
Pavement ATP back by hellocatfood, on Flickr
A page from a zine that I made using Inkscape, Scribus and GIMP
Family Portrait by hellocatfood, on Flickr
All made using Inkscape. Well worth watching the reconstruction made using a Python script
And if you liked that check out my website!