Why not develop a social networking software, with which to exchange bitcoints or other virtual currencies ?

Why not develop a social networking software, with which to exchange bitcoints or other virtual currencies. Either a postcard interface, a wallet and a server side a PostgreSQL database. All with a system of nano-taxation: as long as I exchange on the system I do not pay any tax. When I change I am nano-taxed one for a billion for example. Advantage of the system the market is developing easily. Advantage for the state it can drive and regulate or not the new market, probably world-wide ... Several zones of exchange are possible: Zone dollars, zone euro, zones yuan, zone rubles etc following the course of the currency and The central bank policy of the area.