pygmee (Cédric gémy) is contributing since the first days to the Inskcape User Manual available in SVN. he uses Inkscape everyday as a graphic designer and teaches it in some places such as university courses. He 's also wrote a book about inkscape, published by Eyrolles, in french.
He also uses a lot Gimp, about which he wrote a book in french, and scribus, for which he has been a GSoc mentor in 2008.