Check out Hubski you guys! It's very small right now, but I believe it has a better system to encourage good content. You can filter out anything you don't want to see and follow tags or people you want to see, to create your own feed. When you vote on a post, what you really do is share it with all your followers. The system works very well, even for spam, and it encourages friendly discussion and tolerance, because if you don't behave that way, people will just filter you out and move on.