http://www.commandlinefu.com/commands/browse/sort-by-votes

Discover new command line utilities or combinations of them to solve various things. Learned all kinds of useful stuff. Things like I know but always forget about:

   python -m SimpleHTTPServer

To server the current directory on port :8000

Then there is silly stuff like:

   dd if=/dev/dsp | ssh -c arcfour -C username@host dd of=/dev/dsp

To output your microphone to a remote computer's speaker [note: you probably shouldn't be using arcfour in general for ssh, and it might be disabled on your site].