This story is a sequel to Best Hell Ever

Once upon a time, Twilight went to hell. It wasn’t that bad. It was pretty great, actually. It had a library! A big one. Like, bigger-than-the-universe big. But then Twilight went and got herself kicked out of hell, and now she’s depressed.

There’s only one logical solution: with Starlight’s reluctant help, Twilight is going to break into hell and invade its library. Oh, it’ll be tricky — trying to find one specific location in an infinite dimension tends to be a bit hard — but the infinite knowledge it’ll provide is too good to pass up. Twilight will find that library if it kills her (which, since this is hell, isn’t the worst thing ever in the grand scheme of things).

There is absolutely no way this can possibly go wrong.

Suddenly finding herself in hell, Twilight is presented with one fact: for the rest of eternity, she's stuck in a library holding every book possible. She's expected to organize them and is allowed to read them.

What makes this hell, again?

Now has two Spanish translations, one by SPANIARD KIWI and another by Pugg-Senpai.

Twilight Sparkle wakes up one morning to a harsh dose of unreality. She is stranded, without her friends, on an island which matches no known locale on Equestria. Surrounded and harried on all sides by the alien and the dangerous, she will find her mettle sorely tested, and find perhaps that the best friends you will ever have in your life are the ones you make when your back is to the wall...

Thanks to CedricBale and noobie56xx for tracking down the name of the artist so I could give them credit.

This story is a sequel to Oskar Osäker: Your Worst Enemy

[Prototype 2] X MLP:FiM crossover

Emerald Gleaner once thought the NYZ would remain in her memories and nightmares. But with the appearance of one Sunset Shimmer this terror of the past is brought back to the forefront as Emerald and loved ones dive unknowingly back into the darkness of Blackwatch's heritage.... and there is no running from your past when it is screaming it's fury in your face

A big thank you to More Dakka for the Coverart, Nightmare Knight for editing
(Fimfiction likes to chew up coverart when it's big, if you want to see how it's supposed to look, take a look at my user page.)

One beautiful morning, Twilight Sparkle decides she wants a free salad. After a small amount of theft, assault, battery, and arson, she sits down to enjoy what is sure to be the best tasting salad ever.

...Or she would have, if it weren’t for the Equestrian Intelligence Service locking her up as a potential threat to national security. Now, Twilight must escape a maximum security holding facility hidden deep underneath Canterlot. And to do it, she’ll need a paperclip, a spymare catsuit, an escape plan, and an alliance with the dastardly Drakbog, King of Frogs.

The war has gone on for far too long. To end it, Celestia just has to sign the treaty.

Go read the comments. They're way more interesting than the story itself.

Now with an audio version
Now translated into Russian and with an audio version.

This story is a sequel to A Stitch in Time

Having discovered the message left for her by Star Swirl the Bearded in the distant past, Twilight once again finds herself caught up in the middle of a struggle against forces far greater than herself. In order to even stand a chance she'll need to travel further and wider than she ever has, and forge some unlikely alliances with old enemies. All to bring down the powers that have manipulated and shaped her entire life, and retake control of her own future.

The conclusion of the Time Loop Trilogy, which began with Hard Reset
Available in Spanish thanks to dgs1993
Series TV Tropes page

This story is a sequel to Hard Reset

After the events of Hard Reset Twilight's life and mental well being are slowly returning to normal. Her recovery is cut short, though, when a letter arrives informing her that the time loop spell she cast is causing severe damage to space and time itself. In over her head, Twilight tries to summon anypony who will know how to fix it. The pony she gets is the last one she ever thought she would meet... and nothing like she expected him to be.

Available in Spanish thanks to dgs1993
Series TV Tropes page

I don’t know if I’ve truly died or lost my mind. What is reality, what is sanity? Are they not just a product of society, a unit to be measured? Something that can be judged, evaluated, and constricted by belief, but also something that is limited by our very biology? I’m not really sure, yet I believe myself to be sane, and have decided to embrace my own reality. One born purely from thought, bound by the limitations of my imagination. This… is a tale of ”my” reality, my triumphs, my mistakes, and the sins of a father.

==Originally written spring 2011== Equestria Daily Post==
GLaDOS is free of Chell, free to continue testing, when she discovers a portal gun Wheatley tried to repair with duct tape. When the portal gun catastrophically fails, the enrichment center, GLaDOS, and Chell are literally dropped in the middle of Equestria. The mute test subject soon finds the world of ponies far more welcoming than the human world. But GLaDOS sees possibilities. Let the testing begin... for science.