in no particular order, some ideas:

1. http://mediagoblin.org/

great way for sharing/publishing multimedia and more.
i think(?) you would have to put it behind a http user pass to make it
private.


2. http://syncthing.net/

auto magically sync folders.


3. IRC and XDDC bot?

you have to add ontop https support, is possible, i know of one server
that does secure xddc.

4. like amhi suggested, with ssh access you could use sshfs on the
client to mount the remote ssh file system and so browse it like it was
a drive connected to your computer.
sudo apt-get install sshfs

5. theres more
list of tons of apps of possible interest:
https://github.com/redecentralize/alternative-internet


ive be educated about http://cjdns.info/ and been using it so someone
can remote ssh into my test compiling PC.