I've been one (of the very early) collaborators of the R project (http://www.r-project.org/) which is also Ohloh-listed. For the computer languages that I know and program in, I would like to propose ... [More] to add "S" or better "S / R" ("R" is "GNU S"; there is commercial S-plus; but "R" is now rather a bit more known than S-PLUS). You list 'matlab' among the computer languages; a completely commercial thing. "R" or "S" is very similar but GNU software. [Less]