I am a regular user of OmniFocus, the Todo-list manager by Omni Group. I am very dependent on OF and unfortunately have sometimes ended up with a corrupt database (typical symptom is that many of my contexts vanish). I therefore have set the backup frequency to twice a day, and I backup everytime I quit the program. Moreover I sync to MobileMe. This however has the result of producing quite a large backlog of backup-files that take up space on my harddrive (my OF files are large, because I often end up storing attachments with the tasks). It is tedious to remember to clean up this directory.
This is where Hazel by NoodleSoft comes in handy. With Hazel you can setup rules that are run on the files in a directory. So for my OF backup directory I have a rule Delete Old Backups, that I setup as seen in the figure.
Weird thing: I have to use Date Last Modified because for some strange reason OF sets the Creation Date of the Backup to 13th June 201108:05