Personally I find that many people in the astrophysics department I worked in used either IDL (an abysmal language, for which there is a free GNU compiler) or P

Personally I find that many people in the astrophysics department I worked in used either IDL (an abysmal language, for which there is a free GNU compiler) or Python+Astropy+Numpy+Scipy+Matplotlib (which are all free software). While I really love the work that GNU does, I get the feeling that they have a lot of NIH when coming up with new projects to work on -- maybe they should focus on Hurd or start some new and innovative projects.