They could make a setting to only show retweets if more than N people have retweeted it. I'd love a similar setting for my current stream that relies on favorites.
Come to think of it, I could make that in a few hours...
You have seen http://favstar.fm right? Let me know if I can make it more useful to you. Try the 'my favstar list' feature there - it does what you're talking about.
Come to think of it, I could make that in a few hours...