I recently got around to setting up a backup of my data. I decided rather than using something like Drop Box (which I'm sure is great) I'd keep things simple and set up a new EBS volume on my EC2 box and rsync my data there.
Here was the initial command I used to get the first sync in place manually.
rsync -arvzh --progress -e 'ssh -i path to pub key<path to pub key>'
A quick review of the flags
-a archive mode (preserve timestamps)
-r recurse into directories
-z compress data during transfer
-h output in human readable format
--progress show a nice progress meter (won't want this in script)
-e specify remote shell and put any further args in quotes