Startup Idea : instant social classifieds

when you need something little real quick and you have no one to ask or when you just wanna see if anyone is up. an app where you can post little classified ads that show up real time and has a radius set for everyone so if anyone around you needs, say a cigarette, you can go and offer them one. or if you're moving into a new neighborhood and need a bit of help or just want to meet people. users will be able to post classifieds, write a little description and another user can respond to it :)