Hey, is that an encyclopedia in your pocket? It is if you've got Encyclopodia, an iPod-formatted version of Wikipedia. Yes, that Wikipedia: The sum of all human knowledge. Just think of the facts you'll have at your disposal to impress friends, settle bar bets, and ace final exams (kidding).
All you need is the free Encyclopodia viewer, the also-free Wikipedia e-book files (available in English, German, and Italian), and a pre-5G iPod. For the moment, Encyclopedia works only on iPods up to the fourth generation, not including nanos. (iPhone and iPod touch users can tap the real thing in their browsers, natch.)