Originally Posted by
Lokasenna
Beowulf... hmm... there are better examples, though I suppose it would do. On a similar note, try some Old Norse literature... you can't move for blood feuds! Try Laxdla saga (The Saga of the People of Laxárdalur) for starters... its relatively short, highly readable, and contains a lot of revenge. Njáls saga (The Saga of the Burning of Njál) is even better, though it is longer and heavier going; it is, however, a fantastic tale of revenge!
For Old English, I'd actually suggest Judith over Beowulf - I think the theme of revenge is more clear cut, and its shorter than Beowulf!
As for secondary reading, there are literally hundreds of books and articles on the subject of revenge and feud in Old Norse and Old English literature.