Offsite backup is the way to go if you want your data to survive a fire, but it usually requires costly monthly subscription fees and bandwidth usage. Datto's Box2Box does not.
Datto's previous boxes consisted of an on-site (in your home/office) NAS that uploads its contents onto a server for safekeeping. This Box2Box consists of two boxes, one at your place and one at your friend's, that synchronises between each other. This way there's no subscription fee for online storage, but you still have to transfer the files between the two boxes—a time-intensive task the first time you do it over a cable modem connection.
Although there's no subscription fee, you still have to pay for the box itself, and prices are quite high.
Two 250GB boxes come at $US620, two 500GB are $US660 and two 1TB are $US850. If you're somewhat familiar with Linux, you could build a cheap homebrew version yourself, but for small businesses that don't have much of an IT staff, it's not a bad choice. [Datto]