Using PowerShell to support SharePoint has saved me quite a bit of time. I can do just about everything I would do in .NET, only without firing up Visual Studio just to check a property of a SPWeb object.
I have compiled a collection of PowerShell functions and methods that I commonly use. It's in its beginning stages, but I hope to continue building on it.
[Edit: SPPowerShellPack has been merged into SPoshMod codeplex project. The PowerShell v2 module can be found here: http://www.codeplex.com/SPoshMod)
The files can be found here: http://cid-7475f7deaa12cac3.skydrive.live.com/browse.aspx/Blog%20Source%20Code/SPPowerShellPack There are two files: (1) SPPowerShellPack.bat and (2) SPPowerShellPack.ps1 Edit the batch file and rename to the location where you download the script files to. You will need to download and install PowerShell 1.0 (or greater). Then, just double-click on the batch file to start the PowerShell command window. Examples of PowerShell commands: Display the names of all users in a sub-site (web)
$web = get-web("http://yoursite/subsite")
$web.Users | ft Name, Email
Display the disk usage for a site collection
$site = get-site("http://yoursite")
Display the properties of a feature by passing in a GUID
For more information on PowerShell: http://www.microsoft.com/technet/scriptcenter/hubs/msh.mspx