In Patch 2.1, Blizzard introduced daily quests, the Netherwing faction and nether drake mounts. Through a combination of solo and group daily and one-time quests, players can grind their faction from Hatred to Exalted in as little as 14 days. At Exalted, players can then buy an epic flying mount, the nether drake.
This has been well documented since the patch, but now Blizzard has added their own guide to grinding out the Netherwing faction. Their guide gives a nice overview of the quests involved without too much extra detail. It also links to their Burning Crusade page that covers the origins of the nether drake as well as a trailer.
If you're new to flying mounts, check out Blizzard's guide first. If you like what you see, try WoW Wiki's guide (linked in the paragraph above) for a more detailed look at the quests involved as well as a list of bugs. As for me, I'll stick with druid flight form. And trying to scrape together that 5000 for the riding skill.