I'm in the process of making a blank journal book and once it's finished I'll want something to guide my writing. A few weeks ago I saw a posting on moleskinerie about a template based on Robert Bringhurst's great book, The Elements of Typographic Style. The link led to Rod Graves' blog, where he had a couple PDF templates for a Moleskine journal book. You put the template behind the page you're writing on, and the lines show through the page, helping you stay on course.
But my journal book is 5.5 inches wide and 8.5 inches tall, and I wanted to be able to customize the line spacing, and the other proportions mentioned in Bringhurst's book. Such things are easy using Metapost, which is a programming language for drawing, and TeX to place the images on the page. I wrapped the whole thing up with a Python script.
For example,$ make_template.py -w 5.5in -h 8.5in -m 1.618 -x template.pdf
creates a template for the journal book I made, saves it as template.pdf and opens it using xpdf. The program requires Python, a basic TeX installation, and the xpdf program, if you want the tempate to be displayed automatically.