[mortenjorck]

Assassin's Creed II has some good examples of worthwhile and non-worthwhile side quests. I cannot imagine completing the game to one hundred percent, but half of that is activity which reveals more about the story (tombs, "truth" encodings), while the other half is just numbers (collecting feathers, weapons, and paintings, although I admit to having taken interest in the last one having been an art history minor).