OK, after further thought I withdraw my pay-for-play suggestion.
As someone who has helped build the architecture of the Internet for over 10 years, I know full well the primary reason for its success. Openness. If the Internet was closed in any way, most of you would never have heard of it. In fact things like Firewalls threaten the continued growth of the Internet and future applications.
Also, as a citizen of a free country that allows open criticism of its leaders I can't pursue an action that is intended to shield the people here from new input, whether good or bad. Freedom is wonderful, but expensive and sometimes painful. We just have to take the good with the bad.
As for UBB, it's a nice application with great features and I'm glad that we have it. But it doesn't allow for much user control (like a kill file) since that would defeat it's architecture. So I think the only thing we can do is endure the occasional malicious posting just as we endure offensive behavior on the streets we walk on in the real world.