It’s easy and cheap-free on the micro instance.
You don’t need to be a computer scientist to build one!
Use iotop (thanks Guillaume Chazarain) to figure out (thanks Paul Wise) where the issue is at.
For when you just need to save a file but don’t have time to install a web server…
Build your own Dropbox with BitTorrent Sync and a Raspberry Pi. Because you’re cool like that.