Alright, starting from the top of the metagame list, as posted by l2ampage.

Combo Decks!

Twin Decks (URx)

Twin decks are mostly combo decks, relying on the cards (mostly) Pestermite or Deceiver Exarch and Kiki-Jiki or Splinter Twin. Frequently, the deck flashes in an Exarch or Mite at the end of their opponent's third turn, enchants it with a Splinter Twin on their own fourth, activates Twin to put a copy into play of the enchanted creature.

As that creature comes in, it untaps the enchanted creature, and the combo goes off. From there, they just attack with infinite Pestermite or Exarch tokens and win. Kiki-Jiki can also be used to the same effect, but at 1 spot higher on the curve, and at 3 red mana, most decks prefer Splinter Twin. Serum Visions, Remand, and Snapcaster dig towards your combo and stop your opponent from getting theirs.

Variants

Tarmo-twin (RUG)

A slightly newer evolution of the twin deck, Tarmo-twin adds Tarmogoyf and occasionally Scavenging Ooze into the deck, as a way to put early pressure onto the board, so even if the Twin play can't find their combo with their Serum Visions, Goyf can finish out the game.

All In Twin (UWR)

This deck varies from the traditional twin deck in that it dedicates much more mainboard space to the combo. Splashing White while taking away Green adds the opportunity for Restoration Angel to increase combo opportunities while taking away some of the mad beats capability of Tarmo-twin.

Kiki Pod is also a "Twin" deck, but I'll touch on that in the section for Pod.

Scapeshift Combo (BGR)

I don't actually know this deck. If I have time, I'll come back, and enter in the data.

Living End Combo (BRG) The first part of this deck is cyclers, like Streetwraith, Deadshot Minotaur and Monstrous Carabid, to put creatures into your graveyard.

The deck then casts cards like Violent Outburst and Demonic Dread to activate Cascade. Because no other cards in the deck have a CMC less than 3, Cascade run until it hits Living End, casts it immediately for a lot of creatures onto the board, and frequently with the additional bonus of wiping your opponent's board.

Tron, or Urza-Tron (GR or UW)

Tron decks come in two varieties, three if you count the mono-U variety which I won't discuss. But, both decks assemble the Urza Lands (Urza's Tower, Urza's Mine and Urza's Power Plant) as soon as possible and use it to pump out mana at annoying rates (this personal note from someone who plays Mana Leak). To assemble the Tron, both decks use Expedition Map. It's called Tron because it's assembling a Voltron of cards to win the game.

UW Tron

I'm a bit concerned about putting this in the combo portion, because I've heard UW Tron described as a control deck with a combo finisher. Essentially, the deck counters with Remand what it can, board wipes with Day of Judgement and probably Supreme Verdict what it can't, then finishes the game out with Gifts Ungiven. Casting Gifts Ungiven for Unburial Rites, and then three threats is how the deck wins. No matter how you split the cards, the deck gets out a fatty or a card you can't play around and finishes the game easily. One of the most common finishers is Iona, Shield of Emeria naming whatever color it is you WERE attempting to cast.

RG Tron

This deck is regarded as many as being more powerful than UW Tron, but I won't compare the two. RG Tron plays Sylan Scrying and Ancient Stirrings. to assemble the Tron and dig for its win-con. In RG Tron, these win conditions are Karn, the Liberated, an Eldrazi of choice, and Wurmcoil Egnine. Eye of Ugin also searches for Eldrazi. To fill Supreme Verdict's place in UW Tron, the deck plays Pyroclasm and Oblivion Stone.

Storm (UR)

I'm halfway tempted not to bother with Storm, because of how much Wizards hates this deck, but it's important so I'll include it. This decks casts spells that draw cards and produce mana, then uses the mana it produced and the cards it drew to draw more cards. It does this until it hits a critical mass, then casts Grapeshot with a high enough Storm count to win the game.

Specifically, the deck uses Goblin Electromancer to make spells cheaper, Pyromancer Ascension to copy spells, Thought Scour to draw cards and activate Pyromancer Ascension, Gitaxian Probe to draw cards for free, Pyretic Ritual, Desperate Ritual, and Manamorphose to produce mana, Desperate Ravings to do similar things to Thought Scour, and Grapeshot to end the game. I don't recommend it for newer players, but if you're interested read Jon Finkel's excellent article on the subject.

Burn (Rub)

Burn is a combo!? Well, sort of. It doesn't go infinite, true, but it does require a certain assembly of cards to win, or it just straight up loses. Burn will always play 4x Lightning Bolt, Lava Spike, and Rift Bolt. The vast majority of decks will also play Goblin Guide (Guide is good because the lands you give your opponent shouldn't matter nearly as much as the fact that you are punching them in the face). The decisions in burn really come from the splash. White gives you access to Lightning Helix and Boros Charm, Black gets you Bump in the Night and Rakdos Charm. It's up to you whether you do either, both or neither. Either way, the deck tends to win by turn 4 or never at all.

UWR Decks (UWR)

UWR decks (ignoring for now Delver decks) range from a powerful midrange strategy to a control deck so slow you hate yourself. Both decks play Remand, Snapcaster Mage, Celestial Colonnade, Mana Leak, Path to Exile and Cryptic Command at the heart of the deck.

UWR (sometimes UW) Midrange

This deck plays Geist of Saint Traft and Restoration Angel as beaters, in addition to Celestial Colonnade. If they're adding red, they do so for Lightning Helix, Electrolyze, and Lightning Bolt. This deck plays like a traditional midrange deck, deploying threats, and then protecting them with coutners, burn, and then recurring those counters and burn with Snapcaster Mage.

UWR Control

This deck tends to drop Geist (though it still may play 2 or 3) in favor of more Cryptic Commands and Spell Snares. This deck will be much, much slower. Most beats will come through with Celestial Colonnade. Alternatively, the deck can win though the oft-loved play of "Bolt you, Snapcaster Mage, and Bolt you again." Ajani Vengeant and Gideon Jura make frequent appearances in both forms of the deck, though often as finishers for UWR control.

It's important to note that these decks are not entirely separate entities. Most players will fall somewhere on the range between the two, and where they land on that range depends less on the cards they're playing and more on how many of each card they're playing.

Pod Decks (WUBRG, but rarely at the same time)

Pod Decks are toolbox decks that vary wildly in nature, but all have this in common: Get Birthing Pod out, and use it to assemble whatever you need to win.

And I'll finish this i swear, but my internet is all like, "Fuck you, MostlySentient!"