Check out these hidden meanings in Game of Thrones
CAUTION : Spoilers below proceed at own risk
There are TONS of hidden meanings.
GRRM is a huge fan of chess. In Westeros, however, it is not necessarily "black vs. white" because successful modern literature requires more complex characters than simple heroes and villains. GRRM himself has commented that although Lord of the Rings is a great work of fantasy literature, he wants to move beyond the obvious "bad guys are ugly orcs and good guys are cute/handsome friendly dudes." Those are my words, not his; I'm paraphrasing.
The events of A Song of Ice and Fire are a huge game of chess that is happening in reverse. The king(s) die at the beginning, followed by war/strategy/intrigue/chaos, and in the end there will be two equal but opposite sides. In the world that GRRM has created, it's less like black and white, and more like [black and white and shades of gray] vs. [all the bright and vivid colors].
Or "Ice vs. Fire."Or "Death vs. Life." Or "Hell vs. Heaven."
Also, besides the obvious knights and pawns and kings and queens, the most interesting concepts (to me) are those of rooks and bishops.
In chess, the piece that looks like a castle tower is called a rook. However, a rook is also a bird that is a member of the crow family. So basically... a tower and a crow. The rook chess piece always moves in a straight line - that is to say, "as the crow flies."
There is also a move in chess known as a "castle," which involves moving the rook "inward" and then placing the king "outside" of it. It is used to bolster the king's defenses, and symbolizes having a secret passage to safety - much like the secret passages in the castle of King's Landing. And there's always been that boarded up tunnel below the crypts of Winterfell...
Another interesting piece to consider is the bishop. As the rook always moves in straight lines, the bishop always moves diagonally - in other words, on a chess board that involves a lot of "front to back" and "left to right" movement, the bishop is the piece that will "come at you sideways," so to speak.
THE WAR OF ROSES
GRRM has often talked about how a major historical influence of the story is the Wars of the Roses. The two houses of Lancaster and York (a.k.a. Lannister and Stark) were at war with each other over the throne of England. The Lancaster "sigil" was a red rose, and the York sigil was a white rose. Interestingly, Jon Snow has been thematically symbolized by a blue rose, which does not exist in nature, and science has never been able to create one. It is basically a magical, fictional object in this regard
When the Lancastrian Henry Tudor, a.k.a. Henry VII of England, emerged victorious after years of contention, he solidified his claim by marrying Elizabeth of York. Their sigil became the red-and-white Tudor Rose, and soon after (though not perfectly) things calmed down into a long period of relative peace.
THE CHULHU MYTHOS
According to wikipedia, Cthulhu is "'A monster of vaguely anthropoid outline, but with an octopus-like head whose face was a mass of feelers, a scaly, rubbery-looking body, prodigious claws on hind and fore feet, and long, narrow wings behind.' Cthulhu has been described as a mix between a giant octopus, a man, and a dragon, hundreds of meters tall, with webbed human-looking arms and legs and a pair of rudimentary wings on its back. Cthulhu's head is depicted as similar to the entirety of a gigantic octopus, with an unknown number of tentacles surrounding its supposed mouth." Cthulhu is a death god who sleeps under the sea, and one day he will awaken and bring about the end of the world. I happened to notice that many symbolic elements of the north bear similarities to the tentacled head of Cthulhu - most obviously is the kraken of the greyjoys, but there's also the face of a wolf and the "tentacles" of tree branches.
There are nine choirs of angels, but I'm only going to focus on the "highest" three; the seraphim, the cherubim, and the ophanim.
Seraphim - Their name means "the burning ones," or perhaps more aptly stated as "the ones with the fire." This would likely symbolize the Targaryens.
Cherubim - There are four Cherubim, and each have a different head: that of a lion (symbolizing nobility), that of an ox (symbolizing strength), that of a human (symbolizing wisdom), and that of an eagle (symbolizing quickness). These represent the various "middle" houses of Westeros that are lesser to the story than the Starks and the Targaryens.
Ophanim - These are the most vague and ambiguous of the three, because there is little physical description, and they are most oft described by their "other-ness" to the other two kinds of angels in the top tier of the hierarchy. Get it? They are "Other." They are more commonly known as Thrones. Kind of gives a whole new interpretation to the title, A Game of Thrones, no?