There are so many online data storage sites they offer min. space of 1 GB to Max of 25 GB for free. You need to sign up into those sites and use those space. ofcource no need of these sites because of the CD/DVD and pendrives. You need a broadband connection with higher upload and downlaod speeds to use these services. Instead CD/DVD's are the best options to backup the data and it may took 20-3o min.
here is the list of sites and short description of the sites.
mozy.com 2GB on start up and 512 mb for new contact you reffer.
www.adrive.com5o GB but no desktop client for free users.
skydrive.live.com Which is from Microsoft, offers 25 GB.
boxstr.com 5GB but you can upload 50MB per day using desktop client.
www.getdropbox.com2 gb free space for backing up and sharing your files
www.myotherdrive.com2 gb free space and desktop client.
www.syncplicity.com2 gb free space and another 3GB after you reffer some one.