In the VMware Labs there is a great project called WebCommander. WebCommander displays a small website via IIS and makes it possible to execute Powershell scripts. I've tested it and I think it's great. There are already a whole series of example scripts that are stored and it can be easily extended. For example, I have stored a few Exchange scripts to delete or create mailboxes. Here is a screenshot:
In the basic configuration, WebCommander comes without authentication, but thanks to IIS it is easy to use standard or Windows authentication. The design can also be quickly customized. Here is the link to the project:
http://labs.vmware.com/flings/web-commander
