PSCX is a CodePlex project aiming at delivering high-quality community written add-ons to PowerShell. At release 1.0 now, it provides lots of useful PSH cmdlets, and the list is growing.
Everyone should have it installed, even beginners. One thing it does that saved me a few times, is to automatically setup a transcript (or log) of all of your sessions to a log file that you can refer back to later.
