Have you ever replied to a tweet and realized you want to carry on a real conversation without having to limit your replies to 140 characters? Maybe you met them on Twitter and don't have any other way to talk with them. Just go to TinyChat.com and "Click to create your chat room". In just a few seconds you'll have a URL which you can post or send through direct message to anyone who you wish to chat with. They can click the link, enter a name and be chatting with you instantly.
In the TinyChat Terms of Service (ToS) they say, "After you leave the chat room, all the chat data is gone, so its perfect for secure chats." While they may discard the chat data once you leave, I would caution against considering this a secure method of chatting. The only thing anyone needs to join the chat room is it's URL and the site does not make use of a secure connection.
TinyChat wont be replacing email or instant messaging any time soon, but for those instances where you want a quick and easy way to talk online it's excellent.
Note: TinyChat gives you the option of entering your Twitter credentials. I'm very wary about giving my login information out to anyone, however warhawke tried this and found that they automatically tweet your meeting room information for everyone to see. As always, give your credentials at your own risk.