Telepathy is a project mainly written in JavaScript, it's free.
hive mind
Run this in a directory.
Then run this in another directory.
Then change a file in the first directory.
Then look at the file MAGICALLY APPEAR in the other directory.
Then change the file.
THE CHANGES ARE PROPAGATED.
LOTS OF BUGS
requires the zeromq library be installed on your system:
brew install zeromq