Most of us use instant messaging services from Windows Live Hotmail, Yahoo or Gmail, but how about using instant messaging using Twitter? Twee.li is an adobe air based freeware tool which allows you to chat with your Twitter friends. With this tool, you can talk to whom is following you, see their last tweets and DM them.
You can use only Twitter account to chat in real time with your Twitter network. There is option to view you online friends and also search contacts. Online friends are shown only if your friends are also using the same tool to manage Twitter.