Well, it's going to be hard to say without knowing a little more about the purpose. Del.icio.us was designed so that it was useful to an individual even before

Well, it's going to be hard to say without knowing a little more about the purpose. Del.icio.us was designed so that it was useful to an individual even before the social aspect came into play; Facebook went for saturation in niche markets (college campuses) and then built out. Either of those strategies might or might not work for you, depending on what you're trying to do...