There are lot of Online backup sites but none of the is so flexible.
I have tried many of the most of the offer unlimited data upload... They are so slow that you can never upload so much data
Sugarsync
You can make backups from different machines..no matter how much
You only pay for the data
Machines that I'm syncing online
Imac
Homeseer server
Plugwise server
WorkPC (Documents)
Laptop
PocketPC
They have nice application for Iphone an PocketPc for online access
You can watch all you documents and pictures on you Iphone..
Currently I have 100gb account..Upload was a challenge almost two weeks.
For the non paying customers they have 2 gb version of this services for free.
If you register using the next link they will give you 500mb extra for free
If you go for 30Gb version you will get 10GB extra ( $50 per year)
https://www.sugarsync.com/referral?rf=d0yr5aqaovix9
And yes i will also get some extra space when you use the link