We cross-rsnapshot our servers to other servers in the same datacenter on a daily basis, then to an external site on a weekly basis. It's a bit heavy on disk i/o, but not *that* bad.
I keep looking at customer-driven incremental backup but can't justify the resources or cost for budget services. Therefore, our only offering is whole-node restoration, which we make known to the customer up front with http://ipxcore.com/auptos/#backups even though no one reads the AUP/TOS.....
I know raid != backup but thats as close as I get to backups. Well... Come to think about it, I do have an emailed copy ofmsome mysql databases somewhere. (Forgot what account I sent it to).
My customers data is another thing. But they all run windows environments so their backup solutions are not really usefull here.