I've been meaning to recommend this site for a while - it's got links to a lot of very useful free programs for PC, Mac and Linux covering a lot of things including games, DVD rippers and other graphics programs, education, etc. You sometimes have to check out several different categories to find something, but the links usually work and so far it's never pointed me at bad or malicious software. I've found one wonderful windows arcade game (Typhoon 2001, which is a free clone of the classic game Tempest), and several programs I regularly use for work and at home.
http://www.freedownloadaday.com/
