- On the backend, for the realtime Twitter data analysis, Tweitgeist uses Redstorm which is a JRuby DSL & integration to the Storm engine. https://github.com/colinsurprenant/redstorm https://github.com/nathanmarz/storm

- Redis is used as a queue server.

- On the frontend side: Node.js, CoffeeScript, JavaScript, Bootstrap, jQuery, D3.js

Basically, Node serves a very simple API, everything else is in the browser.

... and please don't be too hard on the UI design, I basically suck with UI :P