Originally started in May of 2006, Carbonite (Windows only, Mac peeps should try Zmanda or Mozy) will backup all the data on your computer as long as it’s connected to the internet - for only $50/year! The service has no upload limits!
My favourite thing about Carbonite is actually the "set and forget" nature of it. Installation is just a single wizard-driven setup executable and an online registration. After which you pick the files you want to back up (by default its My Documents and Desktop) and bob's your uncle! Backup is done is the background over your broadband connection and it picks up when you're computer's idle and slows down when you're working.
The only things to grapple with here is trusting these servers and the time it takes to backup and restore. It will take a few days to backup all my data (excluding programs) but once that is done, it is only incremental backups that take place. A complete restore will take about half that time depending on the speed of your broadband connection's downstream.
Carbonite=$50 yr (link 01, 02)
Mozy=$5 mo. (link 01)
Zmanda=$.20 GB mo. (link 01)