In every event, there are a million offshoots and effects, none really able to be fit into a normal narrative. Here is a collection of one-shots and mini-arcs spun out of The Elements of Harmony and the Savior of Worlds, so knowledge of that series will help immensely. Although I will do my best to make it as accessible as possible.

NOTE!:
All side-stories so far take place after the end of The Elements of Harmony and the Savior of Worlds.
The cast will be varied, as will be the stories, but all are canon.

Chapter One: A Picnic by the Lake: Celestia, Luna and Twilight entertain a guest who is more than meets the eye.
Chapter Two: Time Enough for All: The Doctor has spent nearly nine hundred years in Equestria, most it an extended vacation. But news of giants in Ponyville draw him out of semi-retirement.
Chapter Three: Contact Part One: Old Memories: Chip delivers the Princess' message to President Abernathy, which stirs old memories.
Chapter Four: Contact Part Two: Meetings and Greetings: Equestria makes formal contact with Earth, and an old mystery is finally put to rest.
Chapter Five: Family reunion Part One: The Best of intentions: Dinky sets out to reunite her father with his closest friends, roping her sister and the rest of the Cutie Mark Crusaders on a journey across time and space.
Chapter Six: Family Reunion Part Two: Memories: The TARDIS arrives at Earth, reuniting the Doctor with his past.
Chapter Seven: Shape up or Slaughter Out!: Shining Armor gets some help from an old warhorse to finish what he started with the Royal Guard.
Chapter Eight: How Christmas was Saved... Sort of: A short tale of how Santa Claus was saved one Christmas Or Megan had too much eggnog.

Trope page for The Elements of Harmony and the Savior of Worlds. Story listed there as well.

Equestria Daily page: A man can dream...

Often called a psychotic, meth dealing hillbilly with a habit of untamed violence and murder sprees, Trevor Philips is someone that no one wants to mess with. The body pile he leaves behind and then sets on fire just for the heck of it proves that. But after a particularly deadly drug deal gone wrong, Trevor finds himself in a place even his disturbed mind has difficulty comprehending.

The feeling is mutual for the ponies.

This story is a sequel to An Affliction of the Heart Volume Three: Hybrid

Warden, the broken pegasus, his wife, Kuno the changeling, and their hybrid daughter, Swarm, continue their adventures in a wild, wacky world!

Twilight has developed a device that can detect strange signals coming from outer space; signals from aliens! She gathers her friends so that they can all listen in.

But they may not like what they hear...

cover image courtesy of DocWario

I'd appreciate if everyone could keep the YouTube embeds in the comments to a minimum. The sheer number of them is putting a bit more strain on my connection than I'd like. I'm going to start deleting any comments with 2 or more embeds in them.

If there are three things Principal Celestia can't stand, it's paperwork, princesses and her past. Unfortunately, the first makes up her job... and she desperately needs the second to help her resolve the last.

When Sombra, ex-ruler of the Crystal Empire, is discovered alive and well, Twilight has her hooves full keeping the tyrannical king in check. Instead of the original plan of throwing him in a dungeon or banishing him to Tartarus, Celestia decides to go with the plan that worked out well enough for Discord.

To reform Sombra.

Pinkie takes the job, and gets right to work in helping Sombra become a better pony. Will Sombra finally change from his old, wicked ways and reform? Or will he instead strangle the annoying, pink menace known as Pinkie Pie?

Thanks to the awesomely talented Mickeymonster for letting me use his art! Check him out for even more spectacular artwork!

A close encounter with a category three Kaiju leaves Midsummer Night, a Mark-II Jaeger, in the inky depths of an unknown ocean. With no communications or navigation available, the pilots, Shane and Michael O'Connell, are well and truly out of their element.

Good thing they accidentally brought something with them to liven up the party,

Pacific Rim crossover

Art by: Zeiram0034.
Edited by: Pixel brony.

Now with a Tvtropes page!

Back home from "The Sandbox", one soldier tries to rebuild and restart his life. Though broken and depressed from battle, he is unsure about his place in life. Still living inside the bottle, he discovers MLP:FiM, which gives him hope and motivation to carry on. But his trip to the Central Library one day is what seals the fate of this soldier's future.

A small salute to those who have put themselves on the line and those who are going to.

I love the feedback and i'll try to respond to everything

When Discord hears that his botanical creation, poison joke, continues to flourish in the Everfree, he simply cannot resist a good prank. Poison joke in hand, he storms Canterlot Castle.

Needless to say, the princesses are not impressed. But then, neither is Discord, since the joke also has an unexpected effect on him. And none of them know the cure.

King Sombra’s dark influence was obliterated by the Crystal Heart, and the villain is well and truly dead. But when he attempts to steal the afterlife of an innocent victim, a human spirit is left hurtling towards Equestria, where this unfortunate soul is revived into the only vessel available: the reconstituted body of King Sombra himself.

Thus, a cheerfully oblivious alien is crammed into the form of the most evil and malicious being Equestria has ever known. Not that Shining Armor and Cadence know this, of course. As far as they are concerned, the King is back and he’s lost his fricking mind.

Click here for the TV Tropes page!