It's not just application - it's a brilliant idea. Use-cases - routing, navigation, search, informing. I mean if there is a special layer - the only one click-operation will be needed to open and catch the situation, - just raise your gadget and look through it. No one BIG_BOSS_map could allow customized layers yet. Moreover - very often ritual clauses about "social networking" are just wage desire. In this app (or this future app or future apps similar to this) the social function is clear and touchable