Hopefully it's ok that I'm putting in a nomination...
Title: First Name Basis
Warnings: Alternate Universe
Ratings: 1st-2nd Years
Chaptered/One-Shot: Chaptered (3)
Summary: Miss Granger and Prof. Snape make the awkward transition to Hermione and Severus...or is that 'Mione and Sevie? Throw in a game of MASH and you have a humorous look at the nature of first names.
Link: First Name Basis
Why This Fiction Should be Chosen: It's a very sweet look into the transition of school into adulthood and names. Also, regardless of the fact that I must have read this fic five times, I laugh everytime.