Here is a neat tool to help you see what’s trending on Twitter: What the Trend.
When a new topic becomes popular on Twitter, it’s listed as a “trending topic” at What the Trend. These topics may take the form of short phrases (i.e. Michael Jackson) or hashtags (i.e. #iranelection).
What the Trend provides a constantly updated list of trending topics from Twitter. It also allows users to explain, in a few short sentences, why this item is interesting or important to people right now. Sometimes, it may be a breaking news story. Sometimes it’s just for fun.
The vetted descriptions are syndicated to a broad range of websites and applications. You can see WTT definitions on Twitter.com, in Tweetie or Twittelator for the iPhone, on Trendsmap on the web, or in many other places.