In this page you will find several different categories of software :

 

Recommended software

Software Development Tools

More information and download at the Gnu Software home page. If you are stuck to windows (crime-o-soft (French anagram)) do not worry, the Cygwin solution will transform your PC windows into a GNU compatible development platform. X11R6 libraries and clients available at the same place. Emacs for Windows is also available here

That is all folks for free software but believe me it is already a lot.

Documentation Tools

That is all folks for free software but, again, it is already a lot.

Development Systems

Windowing environment

Real-Time Operating System

OLD Patches for existing software