To find the most useful WMI classes you can use Get-WmiObject, and let PowerShell provide you with a hand-picked list:
Select-XML $env:windir\System32\WindowsPowerShell\v1.0\types.ps1xml -Xpath /Types/Type/Name | ForEach-Object { $_.Node.innerXML } | Where-Object { $_ -like '*#root*' } | ForEach-Object { $_.Split('\')[-1] } | Sort-Object
These are the WMI classes found especially helpful by the PowerShell developers. Just pick one and submit it to Get-WmiObject. Here is an example:
Get-WmiObject Win32_BIOS
