I just decided that I would simply finish leveling my hunter the hard way, but when i can get heirlooms ill make a warrior and follow your guide to 80. I definitly want an 80 warrior for cataclysm... seeing as worgen warrior is going to be a crazy tank! By the way, is using heirlooms with your guides ok? And what class should I be for a tank? I will obviously be switching to worgen anyway but i would prefer best tanking until then. Thanks Jame!
Level 65 unlocks Greater Invisibility. This can be used to instantly escape combat with any enemy, or reduce the damage of big hits by 90%. Keep in mind, when using Greater Invisibility, you will drop combat, and lots of enemies will start evading and healing back to full Health, so do not use this on low Health enemies if you would survive the hit.

If you can Solo an instance, you have two options. The first is to take the place apart yourself and sell all the drops on the Auction House. For level 80 characters, Scarlet Monastery, Uldaman, and other mid-level instances are easily soloable, and are a very popular source of cloth and marketable blue and green items. If you're reasonably well-geared, and feeling more adventurous, Scholomance and Stratholme are also soloable, and can be extremely lucrative as a source of auctionable items.

A "stat squish" and "item squish" was implemented to lower the numbers used in the game, e.g. a legendary item previously with a level of 1000 reduced to 265. Unique class-specific buffs are added back, i.e. mages' Arcane Brilliance and priests' Mark of Fortitude. Titanforging—a random event that raises the initial item level of an item gained via drops or rewards—is still in the game; however, if the item is one of those affected by the Heart of Azeroth, then that item cannot be titanforged.
With Mining, from the moment you take the skill you can make good money selling stacks of the bars or ores in the Auction House. Blacksmiths, Engineers and Jewelcrafters are interested in the bars, while Jewelcrafters and even other miners may want to buy the ores. Make sure to check the relative prices of ore versus bars before smelting. As your skill increases, so does your earning potential. At the maximum level you may smelt Titansteel for a daily fee.

You earn a large rested experience bonus when you log out in this rest areas. This gives you a massive 200-percent bonus to experience gain from most actions (though experience from quests isn’t included). The amount of rested experience you earn increases the longer you’re logged off, and your experience bar will be blue (instead of purple) while you have the bonus.

Also get the Heirloom Mount. Being able to have basic riding speed from the beginning will save you a lot of time if you're starting from level 1. Allied races start at 20, so this is a non-issue for them. It's important to note that Pandaren can not use this mount until they finish their starting zone and pick a faction. Being Horde or Alliance is a requirement of the mount.
Darkmoon Faire: The Darkmoon Faire comes around once a month and provides two ways of bonus XP. You can ride the carousel to get the “Whee!” buff (10% bonus XP for one hour). You can also get the Darkmoon Top Hat by playing a few games, which gives you 10% bonus XP but only works during the Darkmoon Faire. Both of these are generally not worth it for the most part, as you spend more time running to get the buff than you gain in XP when leveling.
Then 8.0 came along and turned everything on its head. Most of the techniques and shortcuts discovered, after 7.3.5 introduced scaling, were nerfed into oblivion. Many of the old techniques were confirmed by myself, first hand, to no longer work. I'm hoping that this thread can serve a similar purpose as the old thread, and gather as much data as possible on the fastest methods under the new system, and facilitate as many different perspectives and opinions on speed leveling with constructive discussion. I've just finished leveling to 110 under 8.1 with the exp curve.