A freak accident causes New York Police Detective Kate Beckett and her partner, best selling mystery writer Richard Castle, to be turned into ponies and transported to Ponyville. Meeting up with Twilight and her friends, Beckett and Castle try to deal with their new bodies, the citizens of Ponyville and all the insanity that the Mane 6 seem to attract, all while trying to find a way home.

TVtrope page found HERE

The Doctor, the last surving Timelord of Gallopfrey, travels through time and space, along with his companions from Equestria.

The Missing Cutie Marks: The Doctor is in, making his debut in Equestria! He soon finds that not all is well, however, when ponies’ cutie marks mysteriously go missing… The "disease" is spreading, and the Doctor must find out what's causing it with the help of his new friend, Twilight Sparkle.

After a major dispute with her queen, a lone female Changeling is banished from her home and forced to be on her own.
She eventually runs into Ponyville where she transforms herself into a random pony citizen to blend in. She ends up running into residents and makes some new friends while exploring.
But then she accidentally runs into a certain young dragon... one who had caught her eye during the invasion of Canterlot.

-My first romance story; but don't expect a clop-fic from me anytime soon, cause I would suck at those.

(In this story, Chrysalis calls her minions by number; please don't ask how she knows who is who.)

The more appropriate artwork to the side is all thanks to 'Tsubaki Rehooved'

The Doctor has had a good, long run through time and space with Ditzy Doo. But it is that time again for him to regenerate bodies. But this time, it seems... different...
What would happen if The Doctor regenerated... as a mare?

This story is a sequel to From the Mouths of Fillies

Dinky and Sparkler have the most awesome godmom in Equestria--that's right, me! Rainbow Dash. Being friends with their mom means I've spent a lot of time with them over the past few years. They're pretty cool kids.

But then ... well, Ditzy got sick. Like, really sick. I've been watching them for her, but if she doesn't get better soon, they may be staying with me for a lot longer than I thought.

That's okay, though: I'm Rainbow Dash. I can handle anything life throws at me.

(Connected to From the Mouths of Fillies, Saying Goodbye, and Feeling Regrets)

Twilight needs to leave town for a mission from Princess Celestia, leaving Spike to watch the library while she's gone. Shortly after Twilight leaves, a certain rainbow maned pegasus come over to read the next Daring Do. But as Rainbow spends more time with the little dragon, she starts to have feeling for him. Meanwhile, Spike also has deep feeling for Rainbow. Can these two finally confess there love, or will they forever stay apart.

Twilight Sparkle wakes up one morning to find she's undergone some changes. She shortly discovers she wasn't the only one. (New cover art by Jamey4 on deviantart http://jamey4.deviantart.com/)

Warning, this work of fiction contains multiple fourth wall breaks, massive silliness, and more than a trace amount of alicorns.
The author may or may not have snapped at times in the writing of this work, and it shows. Bring a towel, you may get wet.

Sora and company crash land in Equestria and discover that Equestria is in the grips of a Heartless attack and race to offer their assistance. They soon discover a dark plot that seeks to use the Elements of Harmony to unleash the power of Kingdom Hearts in favor of a great evil. Takes place around two years after the second game.

When dark creatures begin appearing in Equestria, Princess Celestia and Princess Luna summon the bearers of the Elements of Harmony to Canterlot. Before the six ponies can arrive, though, four strange ponies are expelled from a portal that appears in the throne room, and they explain that Equestria is not the only place at risk from these creatures. Thus begins an adventure that will reveal a greater destiny for Ponyville's librarian than she could have ever dreamed of.

Kingdom Hearts/My Little Pony: Friendship is Magic crossover. Pairings undisclosed.

In the aftermath of a huge explosion in the Everfree Forest, Ponyville soon finds itself as the new home for Lucario, an "Aura Pokemon" from another dimension. While he avoids explaining what has happened to him and where he came from, he repays his new friends' kindness by protecting them from the evil forces that suddenly appears around Equestria.

Meanwhile, a certain princess of the night watches his every move, unable to judge if this new visitor will bring safety or utter destruction upon the land.

(This story primarily takes place between season 2 and season 3. Elements from season 3 and beyond may occur, but won't have a significant impact on the plot.)