Check out http://nodebeginner.org/ , the Node Beginner Book.
This is an unprovoked, unpaid, unrequited plug, just because I enjoyed looking through the site and working out the example. There is ample room to tweak the idiomatic style and play with the example, which is completely straightforward. The writing is a tiny amount sugary, but it presents a very good narrative. This guy needs to write more user guides.