Interactive timeline of the history of English (spread across 10 different "acts") - includes sound clips (including Beowulf and the Canterbury Tales prologue), English language history, etc.
Adding on to Ryan's commentary: For each era, you can click on the different icons and do the following:
1. Read and hear a famous document
2. Get a brief historical overview
3. Linguistic developments
4. New words entering the language
5. A fast fact
6. A pun or riddle