Post-Hogwarts  All stories that take place after Harry would have completed his 7th year at Hogwarts, or graduated, but has nothing to do with book 7.
Post-OotP  All canon stories that take place after OotP was released.
Pre-OotP  All Canon stories that take place before OotP was released.
SIYE Challenges  Stories written in reponse to a SIYE Challenge or contest.
Post-DH/AB  All Canon stories that take place after DH was released and continues after the last chapter where the final battle ends.
Post-HBP  All canon stories that take place after HBP was released.
Alternate Universe  All stories that do not hold to canon.
Holidays  Stories centered around the observance of a cultural or religious holiday such as Christmas, Halloween, Valentines Day, etc. This does not include vacations, breaks, trips, etc .
Post-DH/PM  All Canon stories that take place after DH was released and picks up at the Epilogue or after, Harry & Ginny married with children.