You want a bow that will make people sit up and say "whoah?" You want a bow with a neat mana proc? You want a bow that requires a really, really good PvE guild to get? Here you go.

Name: Black Bow of the Betrayer
Type: Epic Ranged Bow (where are the Legendary Ranged weapons, by the way?)
Damage/Speed: 201-374 / 3.00 (95.8 DPS)
Abilities:

• Increases attack power by 26, always very nice
• On Equip: Succesful melee or ranged attacks will grant 8 mana and if possible drain 8 mana from the target. That's incredible-- it's basically 40-45 mana per five seconds, which allows any Hunter to keep up their DPS for almost twice as long as normal.
• And if you want even more mana, there is a set of mail gloves created by Blacksmiths (dropped by Moam in AQ, I believe) called Black Grasp of the Destroyer that have the exact same proc. And while I haven't tried it out in game, I'm told that the effects of both stack. So with both the gloves and the bow, you'll never need mana again!
• If only Shamans could equip bows...

How to Get It: Such a bow isn't going to be easy to get, and as the name might have already told you, this drops from the Betrayer himself, Illidan Stormrage, at the end of the Black Temple. There is a good argument made that if you're a Hunter able to get to Illidan, you probably aren't going to be worrying about mana problems anymore anyway. But to the victors go the spoils, so kill Illidan, be a Hunter (the mana proc on the weapon makes it just for you animal lovers), and win the roll and the bow is yours. The rest of the world gets to stare in awe at how frighteningly pointy this baby looks.

Getting Rid of It: As far as I can possibly tell, no one has. But maybe there's a guild out there who has Illidan on farm, and just doesn't need it any more. In that case, it's the usual Void Crystal, or 10g 82s 33c if sold to a vendor.