WhereFanfiction.net, so if you have an account over there and really want to write something then you should definitely come and check it out
WhatDarren Shan Saga (Cirque du Freak), Percy Jackson/Heroes of Olympus, or Harry Potter. Other fandoms are allowed for the competition though as long as you ask!
WhenDeadline by 30th of August
more details about the Competition here