Box.com -- 50 GiB free for Android users, includes webdav support

[perspectoff]

Of course, I have 200 Gb webdav from home on my Kubuntu server. It's not that tough to set up a webdav server. I just access it from my Android devices when I'm mobile.

From Kubuntuguide:

http://ubuntuguide.org/wiki/K_WebDAV

I also set up an FTP server pretty easily, and Android has some nice FTP clients (my favourite is AndFTP), as well:

http://ubuntuguide.org/wiki/FTP_tips