Dropbox syncing to 3 machines, one of which is a linux server in my closet. The linux server makes snapshots of the folder and saves rolling daily, weekly and monthly snapshots to a RAID1 array. (see http://neverusethisfont.com/blog/2010/07/how-to-back-up-drop...) The RAID1 array is then backed up to a separate RAID1 array nightly.

Thia has been working pretty well for me and is a good balance between automation and sufficient redundancy.