I started to think about this when I hear from students or friends who are floundering. You know I don't believe in writer's block, but I do understand when someone gets tired of writing badly every day.
So how about a collaborative novel. Maybe two people who aren't getting anywhere can set out together. The usual route is the epistolary one -- two kids exchange letters about their lives, their problems, etc. Maybe they've known each other and one has moved away. Maybe they've met on-line. If a couple of you decide to try this, my advice is to work against the grain -- trade genders, for sure. If you're a female, be a male. If you're naturally snarky, settle down and let the other person be that. Subvert your so-called natural tendencies.
Another possibility is to have a couple of writers simply alternate chapters. Some collaborators agree on a skeletal story-line; some just start and see what happens; a few people I've known go page-by-page, so X would write page one, for example, e-mail that to Y, and Y would write page two and send it back to X. And so on. At a page per day, they have a novel-sized ms. in about four months.
And any novel-sized manuscript is a cause for celebration!