The answer really is to have an electronic exchange with no market maker shenanigans possible, as Alan has mentioned re Overstock.com's plans to create one.

I can't imagine that the big money Wall Street people who profit so hugely from the current system would consent to this, though. There will be all kinds of barriers thrown up to such a system, both legally and logistically. If the brokers don't agree to send their clients' trades through it, then it will be up to the smaller independent brokers like Muriel Siebert which has pledged to use an electronic exchange. If enough of them get on board, it could succeed -- if the SEC doesn't claim that it's somehow bad for individual investors to be rooked no more.