A web-based operating system

EyeOS is a web-based open-source operating system. It's free to use and you don't need to download anything. One of the benefits of such a web-based operating system is that you can access your desktop from every computer with a web-browser and an internet-connection. EyeOS has a lot of online applications built-in: two text-editors (one for .doc and one for .txt), an e-mailprogram, a FTP-Program, a calender, some games, a calculator, a feed-reader and a lot more. You can sign up for EyeOS at www.eyeos.info for free.

OpenLieroX

OpenLieroX is a free open-source worms shoot-em-up game. It'll work on pretty much any operating system, including Mac OS, Windows and Linux. You can download it here. The download is coming with over 60 different levels and also has a multiplayer in it.