I'm using a Raspian distro and running BTSync (http://www.bittorrent.com/sync) to create my own cloud storage (like Dropbox but hosted on my server and free(ish)).
I now know where my files are stored, even if they aren't very interesting to anyone else.
The spec, if anyones interested:
Raspberry Pi Model B running Raspian on a 32GB SD card
500GB WD hard drive (swap partition on this)
120GB no-name hard drive which I can remove and store off site.
D-link powered USB hub to power the Pi and the drives.
1 square foot bit of MDF with holes in it.
Some cable ties
