If you use PowerShell at all and you haven’t at least tried out PowerGUI, you’re missing out. It’s a great product. Think of it as an administrator’s Swiss Army knife. And now think of being able to easily snap new tools into that knife, have them work with each other, and customize them to your liking. Fantastic.
The most recent release raises the bar even higher. Sometime back, they added a very nice standalone (and integrated) script editor. Now that editor includes a debugger. Set breakpoints. Inspect variables. Step through the script. And it’s free. If you do any PowerShell scripting at all and you haven’t tried this out, go get it now.