Auto Syncing Of Folders to External Drive

Hi,

I am looking for some software (ideally free) which will allow a selection of folders on my MacBook Pro's internal hard drive to synchronise with an external hard drive/USB flash drive as soon as it is plugged in.

I have had a search and have found some apps, but they seem to clone the drive or require the destination to be erased (which I don't want).

Thanks in advance for any suggestions.

did you try

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html

Just an idea, but I use Chronosync often, mainly to create multiple copies of images as I shoot them with my camera tethered to the MBP. Although Chronosync ain't free, its worth the money I feel.

So onto my idea, you could use DoSomethingWhen to initiate an apple script when you connect the external drive, the apple script would be used to run a synchronization within Chronosync, that can be set to synchronize certain folders within a volume, or entire volumes. A bit of further research would be required, but it should work, and be very handy too.

Thanks for the suggestions, I'll check them out.