Have trouble finding FOSS software that uses GUI? Are you seeking certain apps that would fit nicely on your GNOME desktop? Then, you should pay a visit to GnomeFiles
GnomeFiles is a software repository which list GTK+/GNOME application exclusively. The website lists applications (in source or binary form) created for the GNOME Desktop and also all GTK+ applications (Unix/Linux/Windows & SkyOS).
The website also list application which uses Gnome/GTK+ bindings such as wxWidgets, pyGTK, GTK#, Java SWT, perl-GTK2, ruby-GTK, etc.
Although GnomeFiles also accepts application submission which is not 100% FOSS, but IMHO, it is a great source to search for GUI application which is supported under Unix-like system, such as GNU/Linux and *BSD.
Visit GnomeFiles at http://gnomefiles.org