Whenever I set up a new Mac mini in the data center (or help someone set up their own to send in) I’ll always suggest to have “Remote Login” enabled whether they regularly use SSH or not. The reason for this is it gives you a second way in if you were to lock yourself out by turning off Apple Remote Desktop or Leopard’s Screen Sharing. It’s easy to do.
For Apple Remote Desktop 3.2 (all one line):
Contents/Resources/kickstart -configure -allowAccessFor -allUsers -privs -all
For earlier versions of Apple Remote Desktop, Apple has a nice document here.
For Leopard’s Screen Sharing:
$ cd /Library/Preferences
$ echo -n enabled > com.apple.ScreenSharing.launchd
(Thanks to this great hint on MacOSXHints.com.)