Im thinking of a 'Widget a day' kind of documentation effort for GTK+. 2.6.x has 177 widgets, and Id take that long ?, I think a month long effort would be valuable.
This GTK+ book is going to be under GFDL, or Open content license.
I'd make some money, if that made it to print[!]. Anyways still looking for support from GNU, and waiting for mentors to keep my motivation levels high.
But anyways, here is day 1: gtkaboutdialog: http://gtkbook.sourceforge.net/aboutdialog.html