Thanks for the info on Jungledisk.
( Jungledisk = First 2 GB free, but it looks like you have to provide billing information before you get the free stuff )
Well Amazon's service does not limit you. They give you "unlimited" space . You literally pay for how much you actually use, hence why they want your billing , so that if you go to 2.1GB they start billing you for the 0.1gb. So you don't "upgrade" or buy more space, you just use and get billed accordingly. If you use less, you pay less.
Jungledisk itself you will pay for the "application" [about $2 a month] and the rest is usage charges. The application is what shines for me, because it mounts this "unlimited" space as a network drive [i.e. like a mapped drive with a letter in explorer] , which means you can use any sync/backup/whatever app you like with it. Amazon obviously have a ton of extra services on top of this space [i.e. sharing files , hosting your website directly on this space etc etc]
You don't have to use Jungledisk [the application] you can sign up directly at Amazon and get the same storage there, but then you need S3-tools to access the drive [firefox actually have an S3 storage addon for this], and it becomes very tecnical . Jungledisk is just one "tool" to easily manage your S3 storage, the best i've found anyway, but certainly not the only one.
Here:
http://aws.amazon.com/s3/
Jungledisk :
https://www.jungledisk.com/ (they have an iphone app too)
Chances are Dropbox and all those on the list most likely use something like Amazon S3 anyway, they just built their own tool on top of it. They make their money by charging for 5Gb when you only use 4GB [and amazon charge them only for the 4GB]
