Shoutbox

http://www.stuffplug.com/

Download that, it has a feature called "talkers".

You can download some new talkers off of the forum I think {?} I'm not too sure though...

To use it you need Messenger Plus! obviously. Also, when installed, go to Plus! > Plugins > Configure, and press "Allow talkers" (or something along those lines". Then in the main IM window, say:

/xtalk {talker name i.e yoda} {what you want to say here}

without the { } obviously.