The best Linux games

http://www.penguspy.com/

Awk basics

http://sparky.rice.edu/awk.html

Quickies: weather forecasts at the command line

http://www.reddit.com/r/bashtricks/comments/b1j5y/get_the_weather_forecast_for_the_next_24_to_48/

Roll your own SSL certificates

http://blog.scoutapp.com/articles/2011/05/10/the-short-and-sweet-ssl-how-to

Find CSS errors more easily

http://www.red-root.com/sandbox/holmes/

Unhide rootkits

http://www.serverwatch.com/tutorials/article.php/3933691/article.htm

Add sar and ksar to CentOS

http://www.unixmen.com/linux-tutorials/1171-howto-install-sar-a-ksar-system-activity-info-in-centos-and-fedora

Keeping files private

http://blog.urfix.com/hide-files-good-linux/