Darkest Before Dawn, by Sessalisk. (EQDaily, GDocs) "Twilight Sparkle is accepted into Princess Celestia's School for Gifted Unicorns and gets a little more than what she bargained for."

Great stuff here. The author's done a good job in imagining Twilight's parents and Celestia's school has some creative quirks. And YoungStudent!Twilight is, of course, absolutely adorkable.