Are you looking for a Dropbox alternative? An open spurce alternative hosted on your own server? I may have found an answer.
The Answer is seafile, a pretty powerful piece of software written in C and Python. I started my own seafile service on this server and am pretty happy with it. There’s only one drawback I have found out: the upload rates are pretty low, which could be caused by crappy ISPs or the encryption of seafile itself. But even Dropbox doesn’t have the best upload rates, so what.
Additionally there are clients for most platforms and even the source code is available, so you can build it yourself, if it’s not available for your platform.
The installation itself is pretty straightforward if you follow the wiki, even if you want some specialties like nginx as your webserver.