The OO-Browser is an advanced object-oriented class browser with
support for browsing C, C++, Common Lisp and its Object System
(CLOS), Eiffel, Java, Objective-C, Python and Smalltalk. It runs
atop Emacs/XEmacs on Linux, UNIX and Windows.
InfoDock is an integrated productivity toolset, mainly aimed at technical
people. It is built atop XEmacs and so has all of the power of Emacs, but with an extended menu-based user interface. Most objections to Emacs use are solved by use of InfoDock.
Jacomma is a framework for developing network-aware reactive information agents, using the ICM agent communication infrastructure. It offers transparent ICM bindings for java, and includes a lightweight agent execution environment.
Orange 3D, a game engine distributed under the zlib/libpng license, is an all in one solution, with IDE, level editor, 2d painter, 3d modeler, and possibly audio editing software all in one clean package, for free!