Ask for, write or read HP drabbles!
Check Cat's Birthday HP Drabblethon at mctabby's lj (the famous creator of Summery Executions).
How this works: Think of a prompt (100 words) for somebody else, and the Sorting Cat will give you somebody else's prompt in exchange.
Look at the already submitted prompts.
Cat's Birthday Drabblethons 2004, 2005, 2006, 2007.