Useful open source software

Ubuntu Linux - A popular Linux distribution - especially good for new users

Gentoo Linux - A source based Linux distribution

Awesome - A dynamic floating and tiling window manager

Spectrwm - A small dynamic tiling window manager

Stumpwm - A manual tiling window manager written in lisp

Xmonad - A dynamic tiling window manager

Fluxbox - A lightweight window manager

Emacs - The text editor which includes the kitchen sink

Vi - text editor (actually vim)

Jedit - an excellent full-featured text editor

LibreOffice - Open source office suite (fork of openoffice)

Gnumeric - a spreadsheet (better math support than openoffice)

Inkscape - a drawing program based on SVG

Scribus - a desktop publishing program. Can also be used for making PDF presentations.

LyX - GUI front end to LaTeX

Gqview - photo viewer

Gimp - photo editor (note the difference with gqview)

Mutt - the command line based e-mail client

[1] - webkit browser with good security features

Firefox - Mozilla's open source web browser

IceCat - GNU free software version of Firefox (no longer maintained)

MozEx - cool Firefox add-on for using a text editor for editing inside the browser (note does not work for Firefox 3.5+)

AdBlock Plus - Firefox add-on which blocks ads

NoScript - Firefox add-on which blocks potentially dangerous Javascript

w3m - a text web browser

Urxvt - terminal with good unicode support

zsh - shell designed for interactive use