I would happily join you! I was going to use NaNoWriMo to work on the novel I started for my senior thesis, but then I got my prompt and I really, really want to write longfic for my recipient. I may split the difference between the two: I'll write my Yuletide story until it's done (probably 20K max) and then go back to working on my original story for the rest of the month. That way I'll have December to obsess over editing/revising the gift fic!