bitstamp requires scanned ID, I can't imagine that someone is trading there apart from using their price ticker.
Many of them are asking IDs... especially in US/EU. I wont be wondered if FBI or Secret Service has a bitcoin Exchange platform. Do not wonder if someone comes to you with a money laundering or TAX questions... I do not recommend use US based exchangers which asks IDs. e-gold, e-bullion, liberty reserve are nice examples...