WoWDB

One of the best world events, in my opinion!  Snowball fights, ugly sweaters, kill the Greench and retrieve Smoky Pastures treats, rescue Metzen the reindeer, gnomes in holiday suits wielding rockets-- wait, what? (Wintergrasp on my realm gets pretty fun this time of year. :)  This is Christmas, World of Warcraft-style!

Don't forget Greatfather Winter's (or his Horde counterpart, Great-father Winter) presents under the Winter Veil tree on December 25.  This is where it REALLY pays to have alts because some presents' contents are determined by RNG.  Those presents can contain exclusive profession recipes, pets, and toys.  The pets don't require a snowball to summon anymore - the downside being that if you summon them outside of Winter Veil, they only last for some-odd seconds before 'dying.'

**Special note: The presents are technically quest rewards.  Some of the 'quests' have required-level restrictions.**

• No requirement
•  Carefully Wrapped Present
•  Gently Shaken Gift /  Gently Shaken Gift
• Level 10
•  Festive Gift
•  Winter Veil Gift (2015 version)
• Level 20
•  Gaily Wrapped Present
• Level 40
•  Ticking Present

2015:  Several new things this year! A MOUNT, new toys (see the new achievement,  Iron Armada) and  Red Wooden Sled,  Grumpling (battle pet), a new weapon illusion, and a new pug costume.  An in-depth guide is available at Icy-Veins.com!

2014:  It seems that  Crashin' Thrashin' Shredder Controller will be special gift for this next Winter Veil.  My goblin character cackled in glee.  Also new:  four lounge cushions (all of which are classified as Toys), three pairs of woolen socks (cosmetic feet), and a  Scroll of Storytelling.

2013:  In fact, datamining done by MMO-Champion of PTR Patch 5.4 pointed to a possible revamp for this grand ol' holiday!  The Winter Veil blog published today by Blizzard confirms that we get a new pet this year called  Rotten Little Helper (not to be confused with the other rotten little helpers).

The "Merrymaker" achievement is part of the meta-achievement,  What a Long, Strange Trip It's Been.  However, not all of the possible Winter Veil achievements are required to earn your Merrymaker title.

Two new achievements were added for this year called  Crashin' Thrashin' Flyer and  The Danger Zone.  The  Crashin' Thrashin' Flyer Controller, required for the achievements, is the special gift for this year.  We already have  MiniZep Controller, so the flyer is a plane (which makes sense considering the name of one of the achievements, /laugh).

This holiday inspires lots of poems, songs, and machinima in the WoW community. I'm still putting together a list of my favorites, so enjoy this (PG-13+) adaptation of a classic by Pyrannor2012. Ok, here we go. If you want to post your own favorites, just reply to this comment! I'd love to see what my fellow Azerothians have found or created.

• Podsafe Christmas Song, song by Jonathon Coulton and video by Mike "Spiff" Booth.
• 12 Days of Christmas WoW/SWTOR produced by GameBreakerTV and featuring Darnell (@darnellsup) from BlizzBlues and "an unnamed SWTOR Sith Assassin on Tatooine."
  Mild swearing, blood elves in skivvies and holographic twi'leks.
• The Christmas Story written by Downbeat and told by Star with additional cast.
  F-bomb in the credits
• Thrall's Christmas Tree written and directed by phenom machinima group AFK Pl@yers.
• Christmas Time in Dun Morogh produced by the Pure Pwnage crew.
• Christmas Party Smash produced by Alin Putinelu. (Video unavailable.)
  
• Santa Baby - Wow style adapted and sung by lilydruid.
  Some sexual innuendo
• Wonderful Dream video by Drascier.
  Some sexual innuendo
• Carol of the Horde adapted by Letömi and sung by Letömi & Kavo.

And talk about blast from the past! Here is Blizzard's Christmas special from 2004! Thanks to Alayea for saving all of those MP3s from the original WoW website. :3

A nice guide to the holiday achievements (not mine):