Looking for books/resources to learn more about LEDs

Hello,

I recently got an Uno, along with this great book called "Getting Started With Arduino" (http://shop.oreilly.com/product/9780596155520.do). I had a lot of fun and boy did I have fun learning the basics! But now that I've finished the book, I wanna keep the momentum going and just keep learning as much as possible. Could anybody point me in the right direction for some good resources or books in the same style as the one I mentioned above? Something that will guide me through projects and help me learn a bit more about LEDs specifically.

Thanks a lot in advance!