pidgin-libnotify is a Pidgin plugin which displays notification bubbles in Pidgin using libnotify and notification-daemon.

Kontact is the integrated solution to your personal information management needs. It combines applications like KMail, KOrganizer and KAddressBook into a single interface to provide easy access to mail, scheduling, address book and other PIM functionality.

Qt is a cross-platform C++ application framework. Qt's primary feature is its rich set of widgets that provide standard GUI functionality.

Metacity is a small window manager, using GTK to do everything.