Hell, I'm not sure I'm up to it *now*, and I just finished it.
Wrenlet's NaNoWriMo Entry, complete, crossover QaF/Dead Like Me. And if you're going to sit there and think, dumb idea? You really need to get out more. Entry link is to the first part, just zoom on through. When it goes up in HTML, I'll link to that instead. But you don't, and I repeat this because I'm like that, don't want to miss this.
Fucking fantastic. Beautifully written, aching, angry, sad and sweet all at once, this wonderful look at an AU of the second season, where Justin's luck had run out.
Nothing I could write here could come *close* to explaining why it's so good. You'll just have to see for yourself.
Someone wiser than I said a crossover should only be written if you can say something in it that you can't say in the original medium. nanowrenlet's done just that. She says incredible things.