Here are some tools you can use with Twitter to find out about trends.
Search tool that can be installed on your browser.
Find out the most favored (saved to favorites) tweets
Keep track of the good and bad with the #GoodBadMe hashtag
find out the most tweeted blogs, images & phrases
Search keywords on Twitter
Find out what twitter’s love, hate, think, believe, feel & wish
Find out the latest links and conversations on Twitter
A search tool that tracks trends, key words & topics
real time twitter analytics from your mobile device
Search Twitter users and topics
Search for the key words, names or the latest trends on Twitter
Find out what Twitter is doing
Find out the most talked about 100 stories on Twitter