That's what I do for my backup server, I have my other server send a WOL packet to it, then on the backup server itself it's scheduled to run the backup job and after the job it shuts down. Once I code a better backup program (basically a front end to rsync) I will probably just run the backups right off my main server using one of those HDD docking stations. Once it detects a backup drive it will run the job then send a report once the job is done.