BabelFish is a simple AddOn for World of Warcraft that allows you to communicate instantly with other players, regardless of language and Faction limitations. As long as you and the other player are running BabelFish, you can instantly communicate in ways that were never before possible!
DL: http://wow.killvoid.com/page.php?id=84&a=dl
to talk in "say": /bf Hi there everyone!
to talk in "yell": /bfy Yo, what's up!
Your message will be translated into gibberish and then sent in the "say" or "yell" channels. The gibberish is special though, and anyone with the addon will understand what you said regardless if they are Horde or Alliance.
Blizzard> Yes, this violates the "Malicious UI Modifications" of the "Exploitation and Client/Server Manipulation Policy" in that allowing Cross-faction communication gives an unfair advantage over other players who are not able to do so, and that this is an intended core game mechanic.
Use at your own risk!
I encountered this yesterday and was testing it with my brother.
Test + Working