This isn't really an exploit nor is it super common sense I believe.
As most of you know 3.2 brought a new BOA item that allows any toon over level 68 to be able to use their flyer in northrend.
Get your level 70 alt their cold weather flying
Pick up your old Riding crop Riding Crop - Item - World of Warcraft
Since you are level 70 you get the extra 10% from the riding crop making you fly 290% compared to most people/farmers who are only going 280%
Just a tip for farmers out there, I started doing this on my 70alt yesterday and you really can tell the difference, and its always fun getting hate tells with ignorant people accusing you of speed hacking because you fly a little faster than them