The first one, which I think could be very useful, is called Nuzzel. Once you log-into the site using your Twitter (or Facebook) account, you’re shown a list of the articles that the people you follow on Twitter are sharing the most. The link is shown first, and then the tweets from the people you follow about it. I think it could really save a lot of time. You can read more about it in The New York Times.
The other site, which is intriguing but I’m not sure how much added-benefit it could bring, is called Nurph. You can read more about it at TechCrunch, but it appears to turn a hashtag conversation into a sort of chatroom (and also lets you replay the tweets in video form). It might, or might not, be an alternative tool for use in Twitter Chats.
I’m adding both to The Best Resources For Beginning To Learn What Twitter Is All About.