Printable Paper with LaTeX and TikZ

A little while ago, I played around with TikZ to make printable paper. As it turns out, this is absolutely trivial, and with just a few lines you can generate pretty much anything you can imagine. Here are the examples that I generated:

A4 paper

Blank Paper
Ruled Paper
Graph Paper
Underlay Paper

Letter size paper

Cornell Paper
Ruled Paper
Graph Paper
Underlay Paper

You can adapt any of these examples to your needs easily, as well as create more complicated layouts. Anything you can find on http://www.printablepaper.net/, for sure. To compile, run the tex file through pdflatex twice.