Over the past couple of months one framework that I have been using is backbone.js this framework for myself is the first one I had come across that incorporated the MVC design patten or Modal View Controller. With backbone.js a developer can now deal with data and the DOM independently and reuse this code elsewhere. On the outside this may seem a trivial thing but to a developer this opens up more opportunities for making feature rich visually and functionally pleasing applications/web sites. For instance the Cavex project undertaken by Linear Blue uses backbone.js to handle the trading screen. In real time traders can actively buy and sell wine and both parties if logged in at the same time can see this happen right before there eyes without refreshing the screen.