Twilight Sparkle and her fellow Elements of Harmony have faced down supernatural foes of the highest order, but sometimes the deadliest danger can come from places one would least expect. As Twilight is forced to bear a devastating secret, her efforts to keep the Elements together may well tear them all apart.
The plotline of the thrilling Pony Psychology Series continues with an exploration of deception, despair and Discord.
This series takes place between Season Two and Season Three.
Secrets and Lies shares the Pony Psychology Series TVTropes page.

After an unfortunate incident involving Rainbow Dash and herbal tea, Fluttershy wakes up one morning to discover that she has turned into a rabbit! With her friends unaware of her plight, Fluttershy must turn to Angel bunny to guide her on her quest to restore her original form. In the process, she is given the oppurtunity to experience everyday life in Ponyville from a whole new perspective, and discovers that there is much more to her friends' pets than she ever expected.

Cover art here if you'd like to compliment the artist: http://mischieflily.deviantart.com/#/d4wfix3

Shining Armor and Cadence's spell reveals something completely unexpected as it expels Chrysalis and her changelings out of Canterlot: A secret kept from everypony for several years...

Now with a TV Tropes page! Warning: Will Contain spoilers.

No, not that kind of tank.

In a world full of magic, mere words can pose a deadly threat. When simply reading a sign can instantly infect the unwary, and cases start to turn up all around Ponyville, Twilight Sparkle casts the only spell she can find that can give her the time she needs to find the cause of the plague. But then she has to figure out how to stop the epidemic... without being able to read.

Editing provided by Spabble
If you like this, try Rainbow Typhoon
Audiobook on YouTube and for download on SoundCloud
Spanish version translated by MIkimoco
Russian version

Twilight finds a dusty old book full of puns and begins to use them, much to the dismay of her friends, considering her puns are slowing down their travels and they need to be PUNCTUAL.

Seriously, a lot.

(Now with a Spanish translation by the generous SPANIARD KIWI!)

Twilight is invited to Canterlot to compete with some of the greatest magicians in the world for the Moonstone Cup, a prestigious award for the most powerful and skillful magicians, unicorn and otherwise. Can she win? What sort of competition will she face?

Awesome cover image was taken from NoOneBahtim

Princess Celestia tires of constantly being surrounded by decorum, deference, and formality, and decides to take a day off from being Princess. But visiting Ponyville incognito is harder than she expects. Will she be able to fit in and make friends without blowing her cover?

After the disastrous invasion of Canterlot, an injured changeling wakes up near a small cottage and is quickly discovered by two of the last ponies she ever wanted to see. Now, with the help of her new "friends," she has to remain undetected in a town high on changeling hysteria that would not hesitate to throw her in the Canterlot dungeons should her true nature be revealed.

Simple, right?

Too bad she couldn't have picked a worse form to stay inconspicuous...

Many thanks to ZuTheSkunk for the cover image!