Anyone ever cowritten a book?

Hi! I didn't have the courage to write a book before and I didn't have a lot of idle time on my hands. I don't even know if I have a talent for it but I have always wanted to write something fun or significant. Since becoming a freelancer, sometimes I'd find myself either too busy with a project or with lots of time to kill after each project. I have thought of getting a crash course to brush up my writing skills and develop my own writing style, unfortunately my want-to-do list takes second priority to my need-to-do list. I haven't co-written anything yet aside from tons of technical papers and reports in the field of microfinance. In my experience, collaborative work enhances the writing experience. So yes, sometimes two heads (or more) are better than one... for as long as you can agree on most things. I'd be interested to do this. I find it quite exciting, even if I would be the first one to admit to being a novice in this field.