Peggy helps you to create GTK applications that run out-of-the-egg. It offers functions to load resources (like .glade files, images, and locales) from a zipped or unzipped egg. It is a thin layer on top of setuptools and PyGtk. It doesn't do anything very fancy, but it can save you from reading some documentation.
Gaze is a lightweight Gmail checker that sits in the system tray and notifies you of new messages in your inbox. You can configure how often the program will use the ROME API to check the Atom RSS feed for your inbox, as well as optional combined notifications, custom browser actions, theming, and more.
DeBox is a desktop environment for Debian-based operating systems. It is designed to not be over-powerful, but rather to be usable and slim enough to leave resources for other programs. Unlike the majority of desktop environments, it does not tightly integrate every component but uses external programs, including ADeskBar, Openbox, the PCMan file manager, and tint2.
The primary aim of the Gtk+2 panel project is to provide a panel that reuses whatever is available (if it is not overkill) in the obvious way, such as subclassing GtkWidget instead of implementing applets, or by using a GtkBuilder file instead of defining a new format to customize the panel. This approach gives some additional advantages for free: you can use common tools in uncommon ways. Above all, you can use Glade to design your own panel. All the dependencies apart from GTK+ are (and hopefully will be) optional.
Final Config implements the preference dialogue (typically found under Edit->Preferences) as a separate application that can be used by another application (called the client application or client) through DBus. The available preferences and how they are to be presented to the user is described in an XML file (the desc file), which can be stored in a place convenient to the client. The client does not need to bother with the desc file; it just needs to pass along the file location when invoking the FinalConfig service.