Dropbox worked well, but the company decided to blacklist it. I suppose some people abused it. While looking for an alternative, I found Ubuntu One. It's funny I never tried it before even though I use Ubuntu. I did not think it was a dropbox replacement, but it is. And you get 5GB instead of Dropbox 2GB limit, which is enough for me (I was a bit above the 2GB limit). It works well under Linux but as well on Android and there is an iOS app I have not yet tried. It also works on Windows and Mac.