Here are some Powershell Commands for Exchange 2007/2010, which may useful for you.
get-user | sort-object name – List all Active Directory Users
get-user "name" | format-list – Infos for a single User
get-mailboxstatistics "username" | format-list – Statisic for a single User
get-mailboxstatistics -server "name" | format-list – List all User with Object Counts
get-mailboxstatistics -server "name" | sort-object -property totalitemsize – same as above, but descending order
get-queue – shows queue
get-autodiscovervirtualdirectory – Infos for Autodiscovery Service
Test-OwaConnectivity -URL:https://mail.domain.com/owa -MailboxCredential:(get-credential domain\user) | fl – testing the access for OWA
test-servicehealth | fl – List all Services with status
test-systemhealth – shows you the systemhealth
Get-AddressList – list your Addresslists
This is a small choice of Commands, a complete List can be found here http://technet.microsoft.com/en-us/library/bb123703(EXCHG.80).aspx
The Part 2 is here: http://tech.m-seidl.com/2010/04/28/ntzliche-powershel
michael