I recently discovered this great application, Cucku Backup at the Pepcom Holiday Spectacular party a few weeks ago. Cucku differs from other network-based personal backup solutions such as Carbonite or Iron Mountain SOHO in that the software is free and leverages existing peer-to peer technology from the Skype VOIP network.
There's no limitation to the amount of data you can back up, and the program is amazingly fast and transparent to the end-user. Once you set it up, the backup software runs in the background, making incremental backups to your local hard disk as well as the "partner" of your choosing which can be connected on your local LAN/WLAN or even over the Internet. Accidentally deleted a critical file? Restores are as easy as a few clicks away.
All you need is two computers running either Windows XP or or Windows Vista, as well as two free Skype accounts. Cucku is built on the Microsoft .NET 2.0 framework, so there's no Mac or Linux version yet, but if there is demand for it, it should be easy enough for the developers to build in Mono.
Have you tried Cucku Backup yet? Talk Back and let me know.