Mahou Shoujo Madoka★Magica

This theory has appeared as soon as episode one aired. In this theory, it is assumed that the world shown during the dream sequence (at the beginning of episode one) was either a parallel world or a previous instance of the current world. In this text, we will be referring to the older instance of the world (the "dream world") as the Old World, and the current instance (the "real world") as the Real World.
This theory stipulates that, for some reason, the Old World has been destroyed. Post-episode one speculations were that Kyuubey was evil and probably was linked to said destruction. Episode two brought a new possible cause. As is commonly believed at this point of the story (episode 2), magical girls and witches might be the same, in that sense that witches might be "fallen magical girls". As shown during the episode, upon killing a witch, a magical girl's seed gets muddier, and the only way to clean it is to use the witch seed. So, a theory is that a magical girl that didn't clean their seed for too long might be turned into a witch. The Old World might just be an instance of a world where witches outnumbered magical girls and brought chaos and destruction to the world.
Whatever the cause of destruction might be, the point of this theory is that the world actually was at the brink of destruction. As we all know, a magical girl can have one wish granted when she makes her contract. So the most commonly admitted possibility is that Madoka, upon seeing the horror of the Old World, accepted to become a magical girl and wished for the world to be restored.
Another possible interpretation is that it is not Madoka that wishes for the world to be restored, but Homura instead. This theory would explain why Madoka doesn't remember anything aside from her strange dreams, while Homura clearly remembers both her and Sayaka. The reason why Homura seems mad at Madoka could also be explained as a remnant from the Old World, where Madoka possibly made horrible things.
While the reset theory is the most accepted, other opinions have risen as well. Some suggest that the dream Madoka had could have happened just a few days prior to the first episode, where Madoka first met Kyubey and Homura by accidentally walking into a witch world. Later, Madoka thought it was just a dream and forgot about it, but Homura realized that Madoka is now in danger of becoming contracted with Kyubey, so she transfers schools to prevent it. Another possibility is that the dream is a premonition of the future, and that the events could happen as soon as episode 3 where Madoka could make a wish to obtain magical girl powers. Let us see that last one more in detail.

This theory appeared along with the World Reset Theory, since they are very similar. Depending on the turn of events, it could be proven valid or invalid as soon as episode 3 airs.
This is a variation of the World Reset Theory. We suppose here that the dream Madoka has at the beginning of episode 1 is the future (or "a possible future" in the sense of the Multiverse Theory). We also suppose that the world is the way it is because of Madoka (that is suggested by lines like "If I could become such a helpful person...That sounds wonderful. Or so I thought.", end of episode 2)
Someone (be it Madoka, Homura or a third party) notes that the only to change this outcome is to travel back in time and do things so that Madoka doesn't become a magical girl (doesn't that remind you of The Terminator ?). From here on, two variations exist:
Variation A: It is Homura that wished to go back in time and stop Madoka before harm is done. That could explain why she was after Kyuubey in episode one, why she already knows everybody, and why she warns Madoka many times. However, the major flaw of this variation is that Homura already is a magical girl, so her wish has already been granted. This variation doesn't explain the dreams Madoka has either.
Variation B: It is Madoka that wished to go back in time, in the hope of making another choice this time and avoiding the fatal outcome. This variation explains the dream, and is consistent if Madoka decided to become a magical girl (and hence use her wish) at the end of the dream. However, it doesn't explain why Homura knows her and try to warn her.

This theory suggests that both the witches and the magical girls believe themselves to be the "good guys." The conflict isn't good versus evil, but rather two groups of good guys fighting for their own methods of saving the world.
The witches are former magical girls who believe that the world is inherently corrupt. They've realized that all use of magic will inevitably lead to the creation of evil forces. They're trying to recreate and purify the world in order to raise heaven from the ashes of Earth. They think that magical girls are only prolonging humanity's suffering in a flawed world.
Madoka will eventually be forced to choose a side. She must either defeat the witches and seal away the power that creates them, allowing humanity to stand on its own, or become the witches' leader and bring about the creation of a new world where everyone can be happy, but at the cost of destroying the existing world.
Kyuubey may actually be on the witches' side. He understands the dangers of magic and hates having to endlessly send magical girls to their deaths, but some spell or curse forces him to follow his assigned role and keep his mouth shut. He's trying to find a magical girl who will turn into a witch powerful enough to break the cycle.
This theory can be combined with The Global Reset Theory: Madoka chose to compromise by restarting the world the way it was, giving everyone a second chance, but with premonitions or subconscious memories in dreams to help them fix the mistakes and regrets of their previous lives. The show could be taking place in this recreated world.

Madoka la que te parte la Roca
La que te foka
Madoka rima con PENIS
no way
Madoka rima con penis
Madoka tiene rabopenis
ERGO
Forcrium TIENE agujeritos. I HAS BEWBS
Madoka me la choca.
ower y yo me pongo celoso y cachondo
Madoka me la toca
MADOKA ME HACE UNA MAMADOKA.XDDDDDDDDD
I'm ok with this
SOON
I'M
FUCKING WITH MUTTHOKA XDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
DJ Madoka in sesion MADOKA + MUTHANNA + Necromancer = MAHOU MUTHANNA NECROTEENA como las compresas zombies, no? no habia unas que eran tena lady? estas igual, pero mas strong MAHOU SHOUJO TENNA LADY
Starring druida as su cachorrito sexual SOLD. A ver traducimos o que herps derps, dejaros d payasadas coño pobre forcriun haciendo el trabajo el solo, vamos a echarle una mano. OIGA PARA CUANDO NARUTURD EN MVFANSUB. rima y todo
BLOWJOB WHILE YOU FAP TO KEINART'S

m1k4 me la pica.
m1k4. . . va poned algo vosotos que no se me ocurre nada :@ @ @