Sure, there's beta readers who might offer suggestions for a later draft or reviewer comments that might influence what happens in the next book, but rarely do readers experience the journey of writing alongside the author.
In the world of blogging and digital publishing, there's no reason this has to remain the case.
Use a Novel Blog to Write an Interactive Story
One of my favorite types of books when I was growing up was the Choose Your Own Adventure series. It provided a quick read or a long one depending on my frame of mind. It was also great to be a part of the story in a way, though the second person narrative style didn't fool me even back then.
A similar paradigm could be used to write a novel, be it a Choose Your Own Adventure style or a traditional novel. A portion of the story could be posted to a blog. It ends with a survey, asking the readers what they think should happen next. Several pre-arranged plot points could be offered to choose from.
A place for comments (open ended plot points) would make it a little more difficult for the writer but all the more interactive.
I have no data to back this up, but I think some readers would enjoy reading a story that they have a say in what happens.
50 Weeks to a Completed Novel
Pick a day to post a new chapter, and post a new chapter each week. Let's say Monday is a good day for you (and for your readers). A 2,000 word chapter is posted each Monday. At the end of each chapter is a survey and comment box to give readers a chance to weigh in on the next chapter.
If this is done for 50 weeks out of the year (leaving 2 weeks for a vacation/holiday), the writer would have written a 100,000 word first draft. If the posts are an average of 1,500 words instead, a 75,000 word novel would be the end result.
Would you enjoy reading a story like this? Would you ever write one?