Information theory is a really cool, really practical form of math / computer science. I highly suggest reading up on it (I'm using this book to get through the basic ideas: http://www.amazon.com/Introduction-Information-Theory-Symbol...).

Basically it has to do with measuring entropy / uncertainty in a message, and I'm finding it has applications almost everywhere, from file compression to image editing to highway design to just the way I talk and communicate information. Fun stuff!