Ever have one of those days where you are working on a database and disable jobs until you are finished. A month later you realize that you weren't doing something that you should have been? I wrote the following script after realizing that another system administrator had disabled a key job "temporarily" and then forgot to turn it back on. The script simply checks the sysjobs table for a key job name that you give it and will email you if that job gets disabled for any reason.
declare @enabled as integer
select @enabled = enabled from msdb..sysjobs where name = '[Daily] ServerName Nightly Backup/Maintenance'
if @enabled = 0
exec master..xp_sendmail @recipients = 'email.goes@here', @subject = '** Nigthly backup job is not enabled **', @message = 'This is to inform that for whatever reason the nigthly backup job for SERVER NAME that should be enabled has been disabled and will not be executed tonight'