I've collected and compiled. These are the merchants (so far) who have generously set out an Advent Calendar or other daily gift for the holiday season. The gifts may not be active until 12/01/2013 and some of them don't start until later in the month.
Any details I have about the prizes are included (ie Advent or 12 Days of Christmas, etc.). I have attempted to get as much information as I possible can. However, I could have something listed incorrectly. Please let me know if you find errors on this list. You can drop a note down the well and I will fix it as soon as possible!
We don't normally list items costing over $1L here at Yer Mawm. Some of the shops listed here, however, do charge a nominal fee for the item or are restricted to group members only. Some of the groups do charge a fee to join. Any items that will cost lindens are clearly marked (provided that I am aware of the fees). Please be aware of this when collecting the prizes. I'll update as I have more information.
I am not affiliated in any way with any of these shops (except .::IM CaPPed::.). I can not help with things like the time differences in Japan or Germany or Nebraska. I simply gather the information and make it available to you.
You can grab a copy of this list from the giant sign on the barn wall, should you need a copy inworld.
Should you run across others or have one at your own shop, please drop a notecard down the well and I'll get the location on this list lickety-split!
Happy Holidays and all that jazz!
22769 - [bauwerk] 12 Days of Christmas (Starts 12/12/13)
A&A Hair Advent - Free
A&A Hair Advent - Free
There are multiple A&A Hair locations. I am not sure whether they give the same gift each day or not.
Aileen's Shabby Chic Advent - Free
Akaesha Advent - (Group Only, Free to Join) - Free to Group Members
ALB Fashion Dream Advent - (Group Only, *$300L Join Fee) Free to Group Members. (This one was free for everyone until 12/9.)
Alice Project Advent - Free
Alice Project Advent (Group Only, *$750L*Fee to Join) - Free to Group Members
AMT Advent - Free
Artistry by ~E~ Christmas Countdown - Free
Aspen Advent - Free
[Atooly] 12 Days of Christmas - Free
Baby Monkey Shoes 12 Day of Christmas (Group Only, *$250L* Join Fee) - Free to Group Members
 beach street  home and garden Advent - Free
Beyond the Mists Advent - Free
By Jove Advent - Free
Celtic Wolf Advent - Free
[coepio] Advent (Group Only, Free to Join) - Free to Group Members
CERO Style Advent - Free
Charisma's Designs Advent (Group Only, Free to Join) - Free for Group Members, There will also be a parcel wide gift hunt which is open and free to all.
CHOP ZUEY 12 Days of Christmas (Group Only, *$350L* Join Fee) - Free to Group Members - Starts 12/13/13
CHOP ZUEY 12 Days of Christmas - Free - Starts 12/13/13 - Chop Zuey has 3 gifts each day. One gift for male members, one gift for female members, and one gift for non-group members.
[CIRCA] Living Advent (Group Only, *$1L* Join Fee) - $1L - $50L for Group Members
Cleo Designs Advent - Free
Delirium Style Advent (Group Only, *$99L* Fee to Join) - Free to Group Members (previous days gifts available until 12/24)
DeVicious Advent ($0L - $99L) One $0L item weekly, once available, all items will remain available until 12/27/2013
Diaa's Out of Normal Store Advent (Group Only, Free to Join)
dirty.little.secret 12 Days of Christmas - $1L daily (Starts 12/13)
DMC - DarkMoon Creations Advent - Free (Accepting donations for UNICEF)
Dragonheart Designs Advent - Free
Drama Libre Advent - Free
Dressed by Lexi 12 Days of Christmas Hunt - $10L each prize
Dulce Secrets Advent *$1L* Daily
//elephant poses// 12 Days of Christmas - Free
EMO-tions Advent (Group Only, Free to Join)
:: envi :: Piercings Hunt Items added each day for 7 days - from Dec 1-9th
Eternal Dream Poses Advent (Group only, *$150L* Join Fee) - Free to Group Members, $10L each day for persons not in the store group
Fab-Fae Advent - Free
Fab-Fae Petites 12 Days of Christmas - Starts 12/12/13 - Free
Fairy Unique Designs Advent - Free
FallnAngel Creations Lucky Advent - Free (If your letter is on the board that day, you get the prize! A different letter each day.) There are multiple Holiday prizes @ FallnAngel. There is a Landmark giver on site that will provide you with all of the locations in the shop.
Forest Mall Advent - Free
FORMANAILS Advent - Free
freebiecosmos Advent (Group Only, Free to Join) - Free for Group Members
Gatsby's Advent - Free
Ginza Jewelry Kohime Advent - Free
Grumble 12 Days of Christmas - Free (Starts 12/12/13)
Heth Haute Couture 12 Days of Christmas - Free Gifts (Also Gifts for Group Members, *$250L* Fee to Join)
*~*HopScotch*~* Advent ($1L Daily)
:.::Hot Stuff::.: Advent (Group Only, *$50L* Join Fee)
Hunt & Hunter Resource Center Advent ($1L daily)
.::IM CaPPed::. 12 Days of Christmas - Free - Starts 12/14/2013
Isis Boutique Advent - Free
JCNY Advent - Free
JFC Bikes Advent - Free
.+*+. Kamiri .+*+. Advent (Group Only, Free to Join) - Free to Group Members
Kinzart Kreetures Advent - Free
KittyCats Advent - Free
KittyCats Winterland Advent - Free
LeCock Advent - Free
Little Christmas Town Advent (Group Only, Free to Join) - Free to Group Members
Loordes of London Advent - Free
The Mad Hattery Advent - $25L Daily
Miss Darcy 12 Days of Christmas - Free
Monastery Advent - Free
Moonstar Advent - Free
Mrs Santa Christmas Market Advent - Free A gift from a different vendor daily. Grab them from the market stalls.
++MRSTYLE++ Advent - Free
needful PIXEL Advent - Free
Nerdy Girl Daily Gift from 12/14 - 12/25
.Olive. 12 Days of Christmas (Group Only, *$250L* Fee to Join) - Free to Group Members
OPAL Jewelry Advent - Free
Paper Doll Advent (Group Only, *$200L Fee to Join) - Free to Group Members
Picture This! Advent - Free
Pillows & Things Advent ($25L daily)
Raynzone Advent - Free
RC Creations Advent (Group Only, Free to Join) - Free to Group Members
The Refuge Advent Hunt - Free - Just find the day's bear to claim your gift.
Rock Cove Advent - Free
Roman's Catz Wild Kingdom Advent (Group Only, Free to Join) - Free to Group Members
Rosen Mall Advent ($5L Daily)
Ruxy's Advent - Free
Shanti Bohemian Advent - Free
Skye Qi's Vintage Apparel Advent - Free (May purchase missed items at a discount)
S.L.A.D. Advent - Free
*Soulglitter* Advent Wishlist (Group Only, Free to Join) One person daily will win their choice of an item. Write a nice letter to Santa, be creative! Include your wishes from the *Soulglitter* store (up to 3 items) Rename the notecard with your SL name. Drop your notecard in the Santa Mail Snail at *Soulglitter*.
StoraxTree Advent - Free
Strange World Community Advent - Free
Sus Store Advent - Free (One for men, one for women)
Sway's Advent - Free
~*Sweet Revolutions*~ Advent Gift Hunt Daily - Free
Timeless Textures Advent - Free
Top Katz Lucky Advent - Free Lucky Advent - Free (If your letter is on the board that day, you get the prize! A different letter each day.)
Tw@ttyC@ke Advent - Free
Twisted Trinkets Advent - Free
The Vamp Realm Advent - Free
USC Textures Advent - Free
Virtual Impressions Advent (Group Only, Free to Join) - Free for Group Members
Virtual Textures Advent - Free
Viviane Fashion Advent - Free
Wildz Creations & Pimp Daddy's Christmas Shoppe Advent - Free
Yasum Designs Advent (Group Only, Free to Join) - Free to Group Members