The current shift of consumers towards E-Readers like the Amazon Kindle or the Apple iPad is amazing. For instance Amazon already sells 143 Kindle books for every 100 hardbacks.
These E-Readers have already a lot of useful features, such as highlighting text, taking notes and finding all the highlighted passages at a centralized location. But surely this is just the beginning of a lot more practical technologies that will be inventend. A video of the innovation agency IDEO provides some food for imagination: