If you've been following the Filly fandom a while, you probably know there's a Filly Wiki containing information about everything in the Filly world! Recently, it's been moved off Wikia and now has its own website at http://www.fillywiki.com/
That website should now be stable enough for general use (disclaimer: I'm the one running the server, so feel free to direct all your technical complaints to me), so feel free to read and edit it to your heart's content!