What's the best app/method to continously back up a folder?

[eroxx]

I want to backup my itunes folder, which is on an external drive and over 300+ gigs ... What's the best way to continually back that up to another external drive?

 

[mjsmke]

Time machine. You can select volumes/folders to include or exclude from the hourly backups.

 

[JTToft]

Time machine. You can select volumes/folders to include or exclude from the hourly backups.

- I second this.