Second, other users benefit from an individual's tags, bookmarks, and so on. And this, in turn, often creates additional value that can come only from the group as a whole. For instance, tagged snapshots of the same scene from different angles can be assembled into a stunning 3-D rendering of the location. (Check out Microsoft's Photosynth.) In a curious way, this proposition exceeds the socialist promise of "from each according to his ability, to each according to his needs" because it betters what you contribute and delivers more than you need.