I've been working on backup systems for a while now (mostly applescripts performing duplicate functions), which led me to start playing around with 'rsync'. Although there are a number of cloning apps out there, and the very good ARrsync program, I felt they were all to feature rich and complex. All I needed to do was to pict a source folder, and a destination folder, and have the first cloned to the latter. I thought being able to chose to have the program delete files from the backup when deleted form the source might be useful, as would an auto run feature; so both are included.
It's simple, useful, but like all scripts you have to be careful, as thre's no going back when a file's been deleted or overwritten. Although it's been well tested I'd say use at your own risk.