THIS ADDON IS OBSOLETE AS OF PATCH 2.3.
ChatThrottler hooks SendChatMessage and listens for the THROTTLED notice. As long as you don't get the THROTTLED notice, ChatThrottler simply passes on the messages to the original SendChatMessage function and you shouldn't notice any change.
If you do get the THROTTLED notice, you have hit the server message rate limit and the server has thrown away messages. ChatThrottler will, when the THROTTLED notice occurs, resend messages and at the same time queue incoming messages. It will send 1 message and wait for the server to echo it (or receive another THROTTLED notice). It will do this until the queue is empty, ater which ChatThrottler will again pass messages directly to the original SendChatMessage function.
ChatThrottler has this slash-command:
/chatthrottler unhook
Using it, will disable ChatThrottler and restore the original SendChatMessage. The setting is not save so ChatThrottler will be enabled upon next login again.