a source code tag system that works the same way across diverse environments. You can locate a specified object in the source files and move there easily. It is useful for hacking a large project containing many subdirectories, many #ifdef and many main()
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)