I've been seeing some buzz the last few days about Spritz reader - an engine for facilitating seriously fast e-reading, and is suitable for really tiny displays. I don't think the engine is open source, but I suspect this is going to be a really disruptive technology. There's an app using the engine that will be bundled with the upcoming S5.
Definitely worth learning about and trying out, especially if you have any interest around developing for tiny displays, like wearable devices: http://www.gizmag.com/spritz-speed-reading-galaxy-s5/31063/ http://www.spritzinc.com/