I had a great time at the Stormwind Stampede yesterday (and pictures and videos from the event should be up soon). But here's a little tip we all picked up from running almost 500 Tauren around the world: to shut down all the yelling, you can just right click on the title of your open chat window, and then go into the "Channels" menu to shut down /yells just like any other chat channel. You can also turn off Guild chat this way as well, just in case your guildies start threatening to spoil Harry Potter, but you don't actually want to /gquit to get away from them. Unfortunately, turning off yell won't get rid of the big red text bubbles when people are near, but all you have to do then is just turn around.
Of course, /ignore still works, and my little level one Tauren now has a bigger /ignore list than any of my other toons, thanks to some rowdy spammers yesterday. And /leave General will get you out of Barrens chat (just as /join General will get you back in when you finally arrive in Ashenvale). And I don't have that much of a problem with this stuff (only when I group up with 500 cows), but if you're really tired of chat spam, Devnull might be an addon worth looking at.
It's not real complicated-- those of you who are experts at chatting (or have just been given a headache before by all the yelling) probably already knew it. But it was definitely a helpful little tip yesterday to sort through all the spam in the channels.