A bit of a cliché but: Emacs. (Or alternatively vi since that can be plugged into most things as well.) As a software developer on *nix I spend a lot of my tim

A bit of a cliché but: Emacs. (Or alternatively vi since that can be plugged into most things as well.) As a software developer on *nix I spend a lot of my time manipulating text: code, e-mail, news, forums, documentation, etc. I can do all this from Emacs which is its greatest strength for me. It might not have the latest and greatest editor features but generally it'll quickly pick them up (within weeks, months or a year someone will have written an Emacs version and I've also written them myself). So I don't have to suffer all kinds of different programs for doing the same activity: manipulating text. Usually all those programs (web browsers, text editors, word processors, news readers, e-mail clients, etc.) only contain a subset of Emacs' powerful editing features. It is also available for a lot of different platforms.