Source: http://lifehacker.com/5986177/build-your-own-power+efficient-diy-remote-storage-system
Cloud storage is everywhere, but if you don't want to mess around with keeping your data on someone else's computer, or you simply don't want to pay for it, DIYer Dominic came up with a solution to use his own computer as a DIY remote storage system over Wi-Fi.
Wake-on-LAN has existed for a while to make it easy to access your computer from anywhere, but it doesn't always work that well unless you have the right hardware, and waking on Wi-Fi is still a little iffy. Dominic needed a system to remotely back up his photos on vacation to safe space on his phone, so he installed Open WRT on a cheap router, and then wired the router to power up the PC when it's pinged. It's an interesting way to roll your own power-efficient storage system, but it's certainly not the only solution. Head over to Dominic's site for a full guide.
Dropping Dropbox + Hardware Hacking | Dom's blog via Hack a Day