Looking for an interesting collaboration? Check out the novel Indigo. The protagonist is an investigative reporter with a secret identity, a shadowy vigilante with supernatural powers, making her one part Lois Lane, one part Batman, with superhuman abilities to boot. When a series of unusual murders plague New York, she seeks out the perpetrators while wrestling with her own strange past.
The book was written by Charlaine Harris, Christopher Golden, Jonathan Maberry, Kelley Armstrong, Kat Richardson, Seanan McGuire, Tim Lebbon, Cherie Priest, James A. Moore, and Mark Morris, with each author contributing two chapters. All chapters are written in close third-person limited narrative, continuing the same story, without indicating who wrote what.
Side note: I attempted to write round robin novels with friends when I was a kid, but sadly, we never completed a full story!