This short script will join a machine to your domain. This can be useful as a post start up script that will launch after a machine has been imaged.

$domain = "DOMAIN"
$password = "PASSWORD HERE" | ConvertTo-SecureString -asPlainText -Force
$username = "$domain\USERNAME HERE" 
$credential = New-Object System.Management.Automation.PSCredential($username,$password)
Add-Computer -DomainName $domain -Credential $credential

Feel free to comment if you have any questions!