Well, this may be common knowledge, but I've seen many posts recently that I thought were common knowledge which a lot of people weren't aware of, so I'm posting my "not-so-common knowledge" stuff now.
For speech display, the WoW developers tried to be "smart" by displaying text above people's heads for an amount of time proportional to the amount of words they say, to allow people more time to read it. For example, if I say "lol" or "i like pie" in /s, it'll be above my head for only a few seconds. But if I say "i exremely a lot like pie for an amount of reasons that you will never even be able to comprehend", it will stay above my head for a longer amount of time because there are more words.
So, here's the exploit. Type any letter or character as many times as you want with spaces in between each one until you can type no more. I use "w w w w w w w w w w w w w w w w w"...repeated as many times as possible. This makes the text stay above your head for about a minute and 30 seconds because WoW assumes that you said a lot of words.
This may sound useless, but it can be used in BGs or arenas to distract the other players and confuse them
Have fun!
-Yamaki