Overwhelms the opponent with immense force.
Key card: Monster Reborn, and other "revival" cards.
Direct Damage (Burn Deck)
Using as much direct damage as possible to deal the fatal blow to the opponent, may also utilize cannon soldiers to sacrifice creatures to deal direct damage to the opponent. If you draw a handful of direct damage cards (or some drawing engine to draw some more burn cards) you might be able to finish the opponent off in one turn.
Key card: Cannon Soldier, burn cards.
All Rounder
Composes of a wide variety of cards, and is not limited to just one strategy. Usually utilizes many powerful restricted cards to take control of the field.
Special Victory
It is possible to achieve victory without having to deplete neither the opponent's life points nor the deck. The Exodia set from Legend of Blue Eyes White Dragon grants victory when all 5 Exodia parts are in hand. For the Japanese version, an alternative is offered - the Ouija Board set from Labyrinth of Nightmare searches out one component each turn with the activation of the "D" trap, and grants victory when all 5 parts have been played.
English Version - Exodia set.
Key cards: Ouija Board: DEATH, or Exodia set.
Weenie Rush
This deck uses little monsters that are levels 4 or below, which can be summoned out in 1 turn, jacks them up with monster enhancements. It also locks the opponent down with cards such as Gravity Bind.
English Version - Key cards: Mechanical Chaser, La Jinn, Goblin Attack Force, Axe of Despair, Sword of Deep-Seated, Gravity Bind.
Japanese Version - Key cards: Gemini Elf, Blood Volrus, sometimes Mechanical Chaser, Strength of Unity, Magician's Strangth, Demon Axe, Gravity Bind.
Race Specific
English - Pharaoh's Servant release makes Machine decks prevalent - Limiter Removal, makes it all possible. Put in some mechanical chaser, Jinzo, and you're unstoppable.
Japanese - With the release of Struggle of Chaos, decks centered around especially warriors have become viable. They have been further powered up with the release of powerful warrior cards, namely Warrior of Sun, and Command Knight in Jounouchi Structure Deck. Machine decks are common because of the power of the restricted card, "Remove Limit" from Thousand Eye Bible, Cannon Soldier, Revolver Dragon (ME), and Android Psycho Shocker.
Monster specific
English - Blue Eyes White Dragon decks using Lord of D. and Flute of Dragon Summon used to be very common, but now more cards have been released they aren't as powerful as they used to be.
Japanese - Decks focused on specific monsters, with other cards supporting it/them. Black Magician decks are possible with Premium Pack 4, while Red Eyes Black Dragon decks with Premium Pack 5. Blue Eyes White Dragon decks are often associated with One Hit Kill decks.
Counter Decks
Seeks to counter all of the opponent's strategies. It is important to understand the metagame since you want to be able to predict what your opponent is going to play and add in counter cards before the game.
Hand Destruction
Constantly pounding the opponent with discard spells, leaving him or her with little choices while you erode away at his or her life points at the same time.
Key Cards - Delinquent Duo, Confiscation, Forceful Sentry, Robbin' Goblin.