I suggested this feature to the author of the Better Twitch TV addon and he added it. In the software if you double click on a line of chat text while on the twitch tv site it does a translate through google translate for the message. While it may not be perfect it allows cross language discussion among people who may not speak the same langauge.
What I would like to see is if i double click on a chatters message in mirc it would do the same go to google translate get the results and replace the message in the chat with the translated text.
This would be a great feature and relatively simple to add.