Yes there is one in the wiki:
Quest Name Requirement Reward
First Blood Complete a game in Play mode. 1 Card Pack
The Duelist Play 3 games in Play mode. 100 Gold
Level Up Get any class to level 10. 100 Gold
Crafting Time Disenchant a card. 95 Arcane Dust
Enter The Arena Enter The Arena 1 Arena Credit (Free Round)
Arrrrrr!!! Acquire every Pirate. 2x Captain's Parrot
Golden Arrrrrr!!! Acquire every Golden Pirate. 2x Captain's Parrot (Golden)
Mrglglglgl! Acquire every Murloc. Old Murk-Eye
Golden Mrglglglgl! Acquire every Golden Murloc. Old Murk-Eye (Golden)
Chicken Dinner Win 100 games in any mode. 300 Gold
Big Winner Win 1000 games in any mode. 300 Gold
Ready to Go! Unlock every Hero. 100 Gold
Beta Hero! Thank you for helping to test our Store! Gelbin Mekkatorque (Golden)
Crushed Them All! Defeat every Expert AI Hero. 100 Gold
Got the Basics! Collect every card in the Basic Set. 100 Gold
One of Everything! Collect every card in the Expert Set. 100 Gold
Ready to Rock! Thank you for attending BlizzCon 2013! Elite Tauren Chieftain (Golden)
Golden Malfurion Stormrage Win 500 Ranked games with Malfurion Stormrage. Golden hero portrait
Golden Rexxar Win 500 Ranked games with Rexxar. Golden hero portrait
Golden Jaina Proudmoore Win 500 Ranked games with Jaina Proudmoore. Golden hero portrait
Golden Uther Lightbringer Win 500 Ranked games with Uther Lightbringer. Golden hero portrait
Golden Anduin Wrynn Win 500 Ranked games with Anduin Wrynn. Golden hero portrait
Golden Valeera Sanguinar Win 500 Ranked games with Valeera Sanguinar. Golden hero portrait
Golden Thrall Win 500 Ranked games with Thrall. Golden hero portrait
Golden Gul'dan Win 500 Ranked games with Gul'dan. Golden hero portrait
Golden Garrosh Hellscream Win 500 Ranked games with Garrosh Hellscream. Golden hero portrait
Greater Reaper of Packs Diablo III Reaper of Souls Collector's Edition 3 Card Packs
Mount Up! Win 3 games in Arena or Play mode. "Hearthsteed" World of Warcraft mount
You are Legend Reach Legend rank in Ranked Play mode. "Legends" Card Back
Fireside Friends Play against other players on the same subnet "Fireside Friends" Card Back
Reaper of Packs Purchase Diablo III Reaper of Souls 1 Card Pack
iPack Awarded for playing a game on iPad. 1 Card Pack
Android Tablet Awarded for playing a game on Android tablet. 1 Card Pack
iPhone Awarded for playing a game on iPhone. 1 Card Pack
Android Phone Awarded for playing a game on Android phone. 1 Card Pack
Samsung Galaxy S6 series Awarded for logging in on a S6 series phone. "Galaxy Gifts" card back & 3 Card Packs
Hero of the Storm Reach level 12 in Heroes of the Storm. "Heroes of the Storm" card back
The exact wording for the Fireside Friends quest is:
Play 3 matches against other players on the same subnet, with at least 3 players total on that subnet.
The maximum amount of packs from Reaper Of Souls that can be redeemed to a single account is 5.
"Ready to Rock!" and "Beta Hero!" are no longer available.
The (Golden) Arrrrrr!!! and Mrglglglgl! quests only require the Pirates or Murlocs from the "Basic" and "Classic" sets. These quests will be retired when the standard format comes around.
The card pack rewards are all "Classic" packs.
I did some research of my own instead of waiting for another answer. I played 4 games with my Level 5 Mage (leveling her up to level 8 in the process). In none of the games did I manage to use the whole deck, but I wrote down all the cards that I drew throughout all 4 games.
First, to confirm Resorath's answer, none of the Level 2, 4, and 6 cards of the Mage ever showed up in the deck, but the original 5 cards that the Mage starts with all showed up in at least 3 games out of 4. So I can conclude that none of the later Mage cards are included into the basic deck as you level up.
Second, exactly ten other cards showed up in 2 to 4 games each out of 4, while no other cards ever showed up. So, only 15 different cards ever showed up for the Mage, some twice, making up the deck of 30. That means, it's not random, and the cards are set in for each basic deck. Most likely, they are tailored to each class. (For the curious, for Mage they are: Murloc Raider, Bloodfen Raptor, Novice Engineer, River Crocolisk, Raid Leader, Wolfrider, Oasis Snapjaw, Sen'jin Shieldmasta, Nightblade, and Boulderfist Ogre, plus the original 5 Mage cards)
Both of those conclusions could be very good coincidences, but, eyeballing the probabilities of these coincidences, I firmly believe that those conclusions are correct.
So, I did not experiment with all 9 classes, but I found my answer: The basic decks were pre-made by the creators of the game, and they do not change as you level up. I guess the results for the other 8 can be found the same way.
Best Answer
So from the looks of things, there aren't actually many Easter Eggs in Hearthstone, at least not many discovered yet. It is indeed a little surprising, but to be fair, Hearthstone isn't exactly the largest of games. The closest things to Easter Eggs are actually more like hidden references to the lore of Warcraft.
There are of course individual cards that are references to things in World of Warcraft rather than the actual lore, one of the most obvious being Leeroy Jenkins, but I wouldn't necessarily define these kinds of things as Easter Eggs.
If individual unlisted extras are discovered, feel free to edit this question and tack them on here, so they can be easily organized. However, from what my research could find, these are pretty much the only ones discovered thusfar.