Libgda is a (relatively small) database access library. It provides a wrapper like ODBC but with more features for accessing several database engines, a general data model for use with CSV or XML files, a metadata extractor that retrieves information about database objects in a common way, and a SQL console application (like mysql, psql or sqlite3 consoles).
AllTray is a program you can use on UNIX and UNIX-like systems, such as GNU/Linux or FreeBSD, running the X Window System. It is used to “dock” application software into the system tray (also known as the “notification area”). AllTray aims to be standards-compliant and work with any desktop environment/window manager+system tray combination that is also standards-compliant.
radare2 aims to create a complete, portable, multi-architecture, Unix-like toolchain for reverse engineering. It is composed of a hexadecimal editor (radare) with a wrapped I/O layer supporting multiple backends for local/remote files, debugger (OS X, BSD, Linux, W32), stream analyzer, assembler/disassembler (rasm) for x86, ARM, PPC, m68k, Java, MSIL, and SPARC, code analysis modules, and scripting facilities. It also has a bindiffer named radiff, base converter (rax), a shellcode development helper (rasc), a binary information extractor supporting PE, Mach0, ELF, class, etc. named rabin, and a block-based hash utility called rahash. Radare was rewritten as radare2, and the old version is only maintained for bugfixes.
gtkaml is an XML syntax and parser that extends the Vala.Parser and transforms all your tags into a valid Gtk+ UI class. It features a casual XML syntax for describing the way Gtk widgets are laid out in a (new) custom widget you're creating. Code "islands" (written in Vala) are used for widget signal handling and other methods/signals/properties that you're introducing. It doesn't depend on an external library at run-time, and it is much more readable than the usual UI boilerplate.
Epris is a D-Bus service and command line client to listen to music. Unlike xmms2 or mpd, it uses GStreamer and D-Bus. It supports all formats supported by GStreamer, and can play both video and audio. It supports gap-less playback thanks to playbin2. It has an extensible command line interface, a small memory footprint, automatic deactivation, and an easy D-Bus interface for other UIs.