a program that examines source code and reports possible security weaknesses (``flaws'') sorted by risk level. It's very useful for quickly finding and removing at least some potential security problems before a program is widely released to the public.
a free user interface builder for GTK+ and GNOME interfaces designed are saved as XML, and by using the libglade library these can be loaded by applications dynamically as needed. (Glade can also generate C code)
Draw Freely, Open Source vector graphics editor, with capabilities similar to Illustrator, Freehand, CorelDraw, or Xara X using the W3C standard Scalable Vector Graphics (SVG) file format. Supported SVG features include shapes, paths, text, etc