The two most valuable scripts are Get-ExchangeStoreageInfo.ps1 and Create-User.ps1
Get-ExchangeStorageInfo gather information about your Exchange databases, storagegroups, file and diskutilization. pretty handy to run now and then to monitor your Exchange storage.
The other script Create-User, creates windows accounts with homefolder, mailbox, joining the account to group, setting permission on folders etc. The script itself is not that fancy and could be more straightforward and smarter. Its intention was to show various techniques that can be used from powershell. One popular thing is to show a windowsform for userinput instead of questions in the script itself.
To make this script work there is a bunch of prerequisite, OU structure, variables, fileshare etc. so you will not be able do download it and just make it work, you have to put in some effort yourself.
The script can be downloaded from http://www.seforum.se/Pages/20088115544100.aspx
