Languages:
4 Ruby
4 Python
4 C/C++
2 Java
2 Lisp
1 HTML
1 Scheme
1 Mathematica
1 Javascript
Editors:
8 Emacs
5 Vim
1 Visual Studio
1 Eclipse
1 Netbeans
Browsers:
8 Firefox
2 Opera
1 IE
OS:
11 *nix
8 MacOS
2 Windows
Possibly modulo a couple of miscountings. If people had multiple programs open (like one person with both Firefox and IE, or my own setup with Windows + Ubuntu VM), both are counted. I omitted obvious jokes, like the Commodore 64 screenshots or Don Knuth's desktop. And it only includes editors I could identify, so whatever you Mac folks are using to edit your Ruby isn't included.