Very good post, I have searched for something like this for a while.
Sadly it doesn't allow "true" stock trading, you can just engage in CFDs where you don't really own the asset. I would like a service more that allows users to trade with stocks directly, although I believe that is not possible by law. Regulations require to identify the owner of a stock and the money he used to buy it, so a "anonymous" platform would not be legally possible.
Still interesting though!