I tried a few online backup services last year: Carbonite, Mozy, ProtectMyPhotos, and Titanize. I use Carbonite to back up my home system, but I have found the Achilles heel of online backup: it's really slow. My first backup of music, photo, and video files over my home broadband connection took, literally, months. Plus, online backup puts my files on someone else's servers. They're probably more secure than my home machine, but it still makes me a bit uncomfortable.
A new service, Crashplan, lets you back up your PCs and Macs to other PCs and Macs, either your own or those of your friends. For example, my wife can back up her laptop to my home desktop. The backup works at LAN speeds when she's home, so it's fast, and we're not sending our data to some unknown server farm. Crashplan backups are encrypted before they are sent out, so I can't read my wife's files.
One of the cool things about Crashplan is you can use it as remote backup for off-site safety, but with the first backup happening locally, for speed. For example, I could have my dad come over to my house and run a backup of his laptop on my home's network. That would take a few hours. But from then on, from his home, Crashplan would perform incremental backups over the Internet. They're slow, but there's not much data to worry about--and we wouldn't have this long unprotected period in which the initial backup is still running. A future version of the product will allow users to perform an initial backup to a removable hard drive and then give that hard drive to a friend or family member for ongoing backups, according to Crashplan founder Matthew Dornquast.
The system can make redundant backups of one system to multiple locations, which is a good idea, since friends' and family computers aren't likely to be on all the time, as a data center's drives are.
Crashplan "buddies" can restrict the amount of storage friends' backups can use on their computers, but other than that the system is hands-off, and in my tests it didn't impact performance noticeably.
Another big plus for Crashplan: cost. Online backup plans charge by the month or by the gigabyte. Crashplan is just a one-time software purchase: $20 for the home version (which backs up files once a day), or $60 for "pro" (which features live backups and keeps older file versions). There's a free 30-day trial available on CNET Download.com for PC and Mac. Crashplan will host a backup for you, at 10 cents a gigabyte a month, but as Dornquast says, "We pretty much beg you not to use it."
I really like the idea of using a loose social network of computers for redundant, off-site backup. Note that if you want to have access to the same files from multiple machines, what you want is something different: synchronization. See coverage of Tubes, FolderShare, and BeInSync for that.