Not all iPhone and iPod Touch apps come with the ability to view and track trends on Twitter, so supplement your mobile tweeting with the Twitter Trends app. Its purpose is simple: It displays multicolored word clouds of “Hot,” “Rising” and “Emerging” trends on Twitter. Clicking any word or phrase — such as “global warming” or “Christmas trees” — gives you a list of recent tweets with that word, including follower counts for the people whose tweets are displayed. In addition to viewing the general trends for all of Twitter, you can also sign up for a Personal Twitter Trend Discovery Account through the application. This will allow you to discover and track trends in the tweets of only people you know. A PTTDA also has the ability to automatically filter the tweets of people you follow into categories based on their content, giving you the power to see only the tweets you care about and none of the useless junk.