software

http://mcosre.sourceforge.net/ The MacOS Re project attempted to build a booting system for old Macs from scratch. The project is now dead but there is source and documentation available on the website.

https://github.com/facebook/fbconsole Post to Facebook from the command line!

http://linuxzoo.net/ LinuxZoo offers a tiny virtual computer and a set of tutorials for learning Linux basics free of charge.

http://www.youtube.com/watch?v=vlDoSv6uDKQ UCLA mathematicians have created a system for automatically arranging furniture.

http://circos.ca/ Circos is used to render genomes attractively. It can also handle any undirected graph. I successfully used it to create a diagram of all of my Facebook friends and their connections. Bonus link: OpenOrd is a plugin for another graph drawing software which can handle very large number of nodes.

http://www.resexcellence.com/ The long-defunct Mac website ResExcellence has returned with its old content. Back in the day this site had all kinds of information about the workings of Macintosh systems and I personally learned quite a bit from it in grade school and junior high. It certainly set me on the path that led me to learning everything I know about software.

http://mywiki.wooledge.org/FtpMustDie A list of reasonable criticisms of FTP.

http://devstructure.com/ Blueprint figures out your server's configuration so you can reproduce it later.

http://codemonkey.org.uk/2011/06/01/red-star-kernel/ North Korea has released its own Linux distribution. I'd love to see the source.

http://www.vidarholen.net/contents/blog/?p=24 This blog post walks through the contents of a private key and shows how to do RSA with it.