We've been running a Hallowe'en Comment Fic Challenge over on spn_bigpretzel over the last month. There were 31 prompts for 31 days of October, and over eighty fics were posted. These ranged between 100 words and 1,500 words, and they're all well worth a read!
From my own point of view, I'm happy that I managed a grand total of eight stories, and here they are listed for posterity!