Have you ever used a service that synchronizes files between computers, over the internet and through firewalls, as well as letting you access those files from their website?
Dropbox gives you 2GB for free and works perfectly. I have been using it for years and I love it.
Microsoft Live Mesh is more powerful. It worked great for a couple years but after March 31 they're discontinuing the beta version...and the new version won't run on Windows XP. The new version uses 5GB of your free 25GB SkyDrive, as well as letting you sync folders between computers without putting them in the cloud. Both versions also gave you a tunneled Remote Desktop connection from any computer (or from their web site) to any computers where you have it installed.
I just found out about SugarSync. I installed it and am using it now. 5GB free and quite similar to Dropbox. Seems to be more powerful and the client is better. Googling it, I've found some people giving it bad reviews for sync conflict resolution problems.
I tried Wuala a while back and hated it. I can't remember why.
I have not tried Syncplicity, SpiderOak, or Ubuntu One, but they seem similar to SugarSync and Dropbox.
There's no shortage of synchronization programs and services. There's no shortage of cloud storage. But, are there any combined ones that I've forgotten? That is, programs that keep your data locally, store it in the cloud, and keep everything synchronized?
How about hacks that accomplish the same thing using existing cloud storage? I've seen programs that mount your GMail or SkyDrive as a local drive, but they don't keep your files locally and sync them; instead they just mount those things as (basically) a network drive.