Reference: List of Online Backup Services

Online Backup Services that offer a 'free' account:

Linux, Windows and Mac:

• SpiderOak (2 Gig free)
• Dropbox (2 Gig free)
• Box.net (1 Gig free) Browser based
• My Other Drive (2 Gig free) Browser and Java based

Linux:

• Ubunto One (2 Gig free)
  

Windows and Mac:

• Mozy (2 Gig free)
• IDrive (2 Gig free)
• ElephantDrive (1 Gig free)

Windows:

• DriveHQ (1 gig free, pause at 50mb,cross platform if you use web + ftp)
  

Online Backup Services that do not offer a 'free' account:

Linux, Windows and Mac:

• Jungle Disk
  

Windows and Mac:

• Backblaze
• SugarSync
• SafeCopyBackup
• Cabonite 
• IBackup
• MobileMe 

Windows:

• Intronis (no pricing info on website or info about free account)

Mac:

• BackJack
  

Others I have yet to look at:

- CloudBerry
- Memopal
- FolderShare
- FilesAnywhere
- Mesh
- SwapDrive
- XDrive
- Steekr
- eSnips
- Yuntaa
- Dropboks
- Omemo
- Openomy
- Yahoo! Briefcase
- MyBloop (interesting, need to take a look)
- SkyDrive
- Drop.io
- Wua.la
- Omnidrive
- in.solit.us
- Badongo
- AllMyData
- DivShare
- MediaFire
- MegaUpload
- OrbitFiles
- ADrive
- Syncplicity
- ZumoDrive
- BeInSync
- Tilana
- MyDocs-Online
- ATT OnlineVault