Matt, Owncloud is a really powerful self hosted cloud storage option.
Some features :
1) Scalable. fire up an owncloud server, add in a few extra hard drives and expand your capacity.
2) Sync what you want. you can syncronize a folder, a few directories, or an entire server.
3) Full Replication (real time ?). You can have 2 or 5 or 10 owncloud servers running anywhere on the internet, and have all of the data fully replicated across those servers.
One of the setups we are looking at :
Client A has 2 locations. each has a fully replicated owncloud server. If one of the sites burns to the ground, the data is fully backed up at all times. We have clients with 2, 3 and 4 locations.
We have 3 tech locations. each location has an owncloud and replicated. In addition, we replicate client A to our servers as well. so Cleint A data actually has 4 real time "backup" sites. Theirs, plus our 3.
Another complimentary product is
FreeNas boots and runs from a USB stick. Uses all available hard drives for storage.
Owncloud will run on FreeNas.
www.HawaiianHope.org - Providing technology services to non profit organizations, homeless shelters, clean and sober houses and prisoner reentry programs. To date we have given away over 1,000 free computers.