Timtravel fic
I thought I had this saved on my HD but I cannot find it:
Harry travel accidentily back in time and ends up working at Hogwarts as the Muggle Studies Prof. He meets ickle Snape at Madam Maulkins and sponors him school robes. Snape gets sorted into Ravenclaw.
I think it was part of either the snarry hols or snarry games or a similar fest, but I might be wrong.