TweetChat helps put your blinders on to the Twitter-sphere while you monitor and chat about one topic.
TweetChat creates Twitter-based online-chat rooms, based on the hashtags feature (for example, #iranelection) of Twitter.
You select a hashtag, and TweetChat creates a virtual "chat-room" that shows you all the tweets that people are posting that include that hashtag in near realtime.
Quickly login with your Twitter credentials to join the conversation.
Good, but could be better. Lacks any sort of directory or promotion of chat rooms. One of the problems with twitter is using it to engage and build relationships with what I call cold followers, followers that have no other relationship apart from following you. Such chat rooms are ideal in taking your twitter relationships to the next level.
Tweetchat is a "must use" for participating in Twitter chats. Not only does it stream the tweets in, but as others have mentioned it allows you to both pause and set the refresh rate - something that many wish NewTwitter and Tweetdeck will some day implement! The fact that it has other key Twitter functions (reply, retweet, favorite) just adds to its usefulness during chats. My only current request is that it had multi-user reply as NewTwitter has adopted, so that replies to retweets or to tweets with multi
Initially used for extremely busy chats, when normal robust twitter clients failed to keep up, I now find myself using TweetChat for all but the smallest hashtag events. TweetChat contains some very nice chat specific features like smart pausing, user control, auto hashtag on posting, and various highlight methods for responses and your own tweets. There is one major feature that is keeping me from giving it five stars and that is the inability to hide RTs. TIP: Create bookmarks or favorites of your favorite hashtags so you can quickly join in.
I am a huge proponent of Tweetchat. I often have two windows open at the same time, one with Tweetchat, and the other of Twitter.com. Tweet chat has pausing capabilities, which are helpful during high volume discussions. I also often use the "favorite" star functionality to grab information I'd like to re-visit at a later time (such as a spark for a blog article, which often comes up during #blogchat #journchat and others!)