Where most IDEs rely on static analysis to give you information about your code, Light Table is based around live interaction with your code. You can eg attach

Where most IDEs rely on static analysis to give you information about your code, Light Table is based around live interaction with your code. You can eg attach to a running browser and inject new js or css code into the page from you editor without refreshing. Check out some of the demos: http://www.youtube.com/watch?v=gtXpOD6jFls http://www.youtube.com/watch?v=gtXpOD6jFls http://www.youtube.com/watch?v=d8-b6QEN-rk http://www.youtube.com/watch?v=d8-b6QEN-rk http://www.youtube.com/watch?v=V2rOTrnqqtg http://www.youtube.com/watch?v=V2rOTrnqqtg Light Table is also designed to be easily extensible, in the same way that emacs is. There is a small core which mostly defines interfaces and the rest of the features are implemented as plugins.