For those of you that work from home like me.. how do you back up your work? What system do you use? I have two external USB drives that I mirror and a RAID 1 enclosure.
I back up all my stuff to an external drive every week. My dad backs up his stuff computer stuff online, and to an external hard drive, and backs up all online stuff to online service using carbonite.com
For the most part, I think just about everyone here is going to say "external hard drive". It's just the easiest way.
I use SecondCopy - http://www.centered.com Daily backups to a separate internal drive. Weekly backups to an external drive that I keep "off site". For everyone who uses an external drive - you should seriously think about keeping it at your friends or parents place. Or even in your car. Not much use having a backup if you keep it next to your PC (fires, floods, burglaries etc...)
Time Machine (for Mac) rocks - just plug in an external hard drive and forget it. For the really important stuff, I keep an identical hard drive (with mirrored data) at a location away from my home.
Thats just some of the reasons why I use & sell Iron Mountains services. If you are serious about your business then offsite backups is a must.