A few years ago, two prominent writers - romance writer Jennifer Crusie and mystery writer Bob Mayer decided to team up together and write a romantic mystery. The result was Don't Look Down, a book that received praise for its content, and press for how the authors teamed up to collaborate on such a project.
Since then, not only have Crusie and Mayer finished a second book together, but they've posted a blog that instructs on writing. Though the blog is now dead, just like with Miss Snark's site, there is a wealth of information left behind for writers to mine and enjoy.
The blog (called He Wrote/She Wrote) deals a lot with craft, and touches on numerous topics. Getting to know more about them is also wise if collaboration with another author is in your future.