Etherpad + plugins and many other extensions (check out the various branches). I'm available for consultancy hacking on etherpad.
Java JavaScript Scala Other
Pull request Compare This branch is 11 commits ahead, 15 commits behind ether:master.
Latest commit f5858f4 Jan 16, 2012 Egil Möller Merge pull request #1 from elrik/master
Here is the fix for the copyPad plugin

README.md