Here's a neat tip from Amiyuy of the WoW Ladies Livejournal group. Personally, I don't mind the "fog" effect that sometimes pops up in game -- I experienced it most recently while doing OS the other day, though it pops up on the haunted Borean Tundra coast and a few other places ingame as well. But a few people don't get along with it too well; like the drunken blur effect, it can be somewhat overwhelming for those with a weak stomach.
Fortunately, there's a way to turn both of those off -- you just have to dive into the config.wtf file in your World of Warcraft installation's WTF folder (open it up with Notepad on Windows or TextEdit on Mac, though be careful in there, and save a copy before you do it: if you accidentally edit anything else, it could cause problems on your game), add SET ffx "0" to the end of the file, save and close it, and then you shouldn't see that fog effect any more.
You should note that this change will also get rid of the Full Screen Glow effect, apparently, and presumably any other major effects that Blizzard might add to the game in the future. These shouldn't affect gameplay at all -- all they do is change how the local client renders the game's graphics. And especially if you're partial to getting a little green when the screen goes all swimmy, one little code change could help you keep your constitution intact while playing.