how do you back up data on your home computer?

[Doug]

Hello:

A late endorsement for dropbox.com for files you work on using a half
dozen computers and/or virtual machines.  For my physics papers, I no
longer have to carry the right USB stick - which I certainly would
misplace from time to time.

The service is free from < 2 gigs, something like $10/month for 50
gigs.  If all my computers fail, I still have a backup.  The backup is
on multiple machines, and their machines.  I really like not having to
store in my own limited memory what computer I need to use for what
data.

Doug