IIS Process ID for pool
Solution 1:
Use SysInternal's Process Explorer - It will show the command line for the proces, which shows the AppPool Name.
Solution 2:
Run CMD as Administrator, run C:\Windows\System32\Inetsrv\appcmd.exe LIST WP
Solution 3:
c:\windows\system32\cscript.exe c:\windows\system32\iisapp.vbs