MathJax — MathJax is an open source, Ajax-based math display solution designed with a goal of consolidating advances in many web technologies in a single definitive math-on-the-web platform supporting all major browsers. (via Hacker News)
EtherPad Source — released as part of their Google acquisition. The announcement says: Our goal with this release is to let the world run their own etherpad servers so that the functionality can live on even after we shut down etherpad.com. This is the resolution to the bad reception of the news that EtherPad would close in March with no plan B for users. The cult of entrepreneurship worshipped the customers only as a vehicle to an exit, but I don’t believe that it’s moral to do well personally but leave your customers high and dry. This is a message that the EtherPad founders seem to have got loud and clear.