Start or stop a service (SharePoint 2013)

Get-SPServiceInstance | Where-Object {$_.TypeName -eq 'Microsoft SharePoint Foundation Web Application'}

Stop-SPServiceInstance -Identity 85017208-c7ef-4c8d-9a7e-07a9dfd63744

http://technet.microsoft.com/en-us/library/ee704549.aspx

http://sharepoint.stackexchange.com/questions/19709/powershell-get-spserviceinstance-the-term-get-spserviceinstance-is-not-recog