Your own simple dropbox! Cheap android device and bittorrent sync

1) Obtain an android device - if you want more space, get one with a SD card slot

2) Install bittorrent sync on it and on any other device that you want files synced

3) Go through "registration procedure" so that each device knows about every other device (see bittorrent sync docs for this)

4) Enjoy

This really is great.  It synced files when both devices were on the same local network, or even just over the internet.  It is amazing that it can get through a firewall ( it asks if you want to change settings to allow it to get through your windows firewall).