Gabber is a Jabber client for GNOME. Jabber is a flexible distributed Open Source instant messaging system. It also happens to allow communication with other instant messaging systems, such as ICQ, AIM, Yahoo!, MSN, and even IRC. Gabber aims to implement quite a bit of Jabber's functionality while remaining easy to use.
GCompris is an educational software suite with numerous activities for children aged 2 to 10. Some of the activities are game-orientated, but nonetheless still educational. These include computer discovery (keyboard, mouse, different mouse gestures), algebra (table memory, enumeration, double entry table, mirror image), science (the canal lock, the water cycle, the submarine, electric simulation), geography (place the country on the map), games (chess, memory, connect 4, oware, sudoku), reading practice, and others (learn to tell time, puzzles of famous paintings, vector drawing, cartoon making, etc.). It currently offers in excess of 100 activities, and more are being developed.
gRio500 is a Gnome/GTK program that lets you interface with the Rio500 MP3 player by Diamond/S3/SonicBlue. You can currently create/delete folders, add/delete songs, format memory, rename folders/songs, automatically downmix/resample MP3s during transfer, and preview MP3s (play/stop controls). You can interface with both internal and external memory (Smartmedia).