Citytweets.com is real time world map that allows the user to view their specific location details. It provides country, state, city and street details of a twitter user. Now we can easily locate ourselves, family and friends. 
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Tweetburner.com is a web based tool for shortening links which can be helpful for sharing links on twitter. It can also track links shared on twitter. 
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TwitterFriends allows you to view stats of any Twitter user. 
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