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.
Gaby is a small personal database manager using GTK+ and GNOME (if available) for its GUI. It was designed to provide straight-forward access to the types of databases a casual user would normally use, while keeping the ability to easily create databases for other needs. It was designed with extensibility in mind and relies heavily on plug-ins.
GAG is a Graphical Boot Manager with a lot of features. It doesn't need a partition, it works with primary and extended partitions in every hard disk, it has a lot of icons, it allows you to put passwords for each operating system, it can swap hard disks and it can be tested from diskette. The SafeBoot feature allows you to boot your hard disk even if GAG is overwritten. It includes extensive support for many languages and keyboard types.
Pidgin is a GTK2-based instant messenger application. It supports multiple protocols via modules, including AIM, ICQ, Yahoo!, MSN, Jabber, IRC, Napster, Gadu-Gadu and Zephyr. It has many common features found in other clients, as well as many unique features. Pidgin is not endorsed by or affiliated with AOL TimeWarner, Microsoft, or Yahoo.
Gale is an open-source messaging system. It provides private messaging and public chat, uses strong end-to-end cryptography for security, and supports a distributed server network with a range of clients (both console and GUI) available. Gale is currently in early alpha testing. See the homepage for the details of its current status.