This is pretty neat: an implementation of Vi in the browser. You can open files
from multiple sources, including Dropbox. In fact, I'm writing this post using
it right now. It looks like it uses another project called filepicker.io to
handle files. After authorizing my dropbox and opening this file, I was able to
save directly to dropbox by issuing a :w. Things will get really interesting
if you can configure it to load a .vimrc from Github or something...