a common method of creating interactive content. It is slowly being outmoded by newer technologies, although it is still in very widespread use and is worth learning.
an web application which supports online code reviewing. CVS, Subversion, Clearcase, Perforce, Visual SourceSafe and Bugzilla. There is a plug-in architecture for supporting other SCMs and issue tracking systems.
a free user interface builder for GTK+ and GNOME interfaces designed are saved as XML, and by using the libglade library these can be loaded by applications dynamically as needed. (Glade can also generate C code)
open source high performance realtime 3D engine written and usable in C++ and also available for .NET languages. It is completely cross-platform, using D3D, OpenGL and its own software renderer.