As suggested, instead of a doing a gift exchange where authors are assigned to stories through the system, we'll try a less formal structure, where folks can put up their prompts and authors and artists are free to choose the prompt of their choice. Right now I have a help ticket in to the good folks at AO3, asking how to change this year's DtCA from a gift exchange to a prompt meme and how it all works. Once I have that info I will set up the 2014 exchange and open it to prompts.
Also as requested, please note that your prompt may be answered by an artist (or vidder) instead of an author, so if you really only want fic, you will probably have to state that in your prompt.
A full set of FAQs regarding the 2015 Down the Chimney Affair will be posted as soon as I get things set up.
Thank you for your support, oh awesome fandom!
P.S. Feel free to cross-post anywhere you like.