There are a huge collection of application for Twitter. In this site, there is a long list of those applications. I hope these will surely helpfull to you.
Twitter is a micro blogging platform which allows you to publish short messages of less than 140 characters through different mediums like IM, cellphones and the web.
It has a social element as well, as it allows users to befriend and monitor each other’s messages or updates. So what you have here is a publishing tool that can be either public and private.
It is similar to an IRC channel although messages are displayed less rapidly. Some have called it a slower version of internet messengers.
Best Twitter tool I have found so far – Tweepular June 14, 2009
A new Twitter tool June 6, 2009
Friend or Follow is pretty self-explanatory, you enter in your Twitter username and it gives you three tabs of information.
Following (who your following, but not following you back), fans (who’s following you, but your not following them back) and friends (people who you follow and they follow you back.
Twitter.grader April 10, 2009