Tee is rather helpful when building big pipelines of commands. It writes out what it gets on stdin to the console, while also sending it's input on to the next stage of the pipe line. It can also be helpful when you want to capture the output of some commands to a file, and get the output to console at the same time.
ps aux |grep dave |tee |awk {'print $1'}>daves-pids
The command above would show a listing of all processes listings that contain the string dave, and put all the pid's into a file.
Exclusive The man behind Google's $4.6bn plan to become a national wireless broadband provider in the US has ruled out a similar move in the UK when spectrum is auctioned off over the next two years.
Doubt is a pain too lonely to know that faith is his twin brother. - Kahlil Gibran