Programming on Linux

Linux provides a wonderful programming/development environment (just like most/all Unices).

Languages, compilers, scripting...

First there are the usual suspects such as the GNU Compilers, The Pascal/Modula/Ada family tree of languages, Fortran and scripting languages such as TCL, Perl and Python, and of course Java.

Widget Sets

Secondly there are several GUI development widget/theme libraries, the most significant being Qt and GTK+, with GNUstep and Tk not far behind.

Visual Programming

And thirdly, "visual" development environments are now arriving on the scene thick and fast, both commerical and free.

Fortran 90

Commercial Fortran 90/95 compilers for Linux are readily available; free compilers are to be found, but less easily...