iTrends is an iPhone app that can simply lets you find out what are the current trending topics on twitter and also tells you the news behind why is it trending.
It will search for lasts tweets of the the trending topics and give you the option to search on Google also or in other news website.
Available here in the App Store for free!
Pros & Cons
|very simple interface|
|It’s a Free app!|
|No need for Twitter login|