VIM text editor
Vim (Vi Improved) is an immensely popular text editor that could very well be installed in your Linux distro. It is one of the more popular Vi replacements, possibly because it is as scriptable as Emacs.
Vim's primary author Bram Moolenaar releases Vim as charityware: people who so inclined can "pay" for Vim (and encourage its further development) by making a donation to Moolenaar's favourite charity. See http://www.vim.org/sponsor/index.php for more information. Payment can be made in a number of ways, including PayPal.
This time VIM was nominated by William.