Roll

Remember to stop and drop beforehand to dispell fire effects

Please note you can also roll backwards by moving backwards while casting Roll. This is a handy trick if you need to escape without rolling into more enemies.

Avoid casting Roll while you jump, the height will also count as travel distance and considerably shorten the distance you roll. Roll will also stop if there is anything in the path that you couldn't run through such as a fence. Also, be careful not to Roll off cliffs (such as the poor Monk that accidentally rolled off the ledge in Dire Maul East).

Roll can also be used to travel faster through water, but if you are near the bottom it might also roll alongside the ground instead of straight through the water.

For Brewmasters, you can Roll (preferably backwards) and cast Clash immediately after to stun the target. If you pick the target farthest back, you can usually stun an entire group this way. (WoD: Clash has been removed.)

Unfortunately, having Roll does not improve your chances at rolling for items.

There's quite a lot of roll playing going on in the Pandaren starting area.