All Public Call 2014 prompts/requests are now public on AO3.
You can write treats (additional stories) for the participants whether or not you're signed up for the challenge. Just pick a prompt, write, and upload your story to the Public Call 2014 collection, gifting it to the recipient in question.
We're revealing fest entries approximately one a day, which will take us through about three weeks of December. Treats will be revealed on the 21st - that's how long you have to write and upload them. :)