jgraphpaper is a simple application written in Java for generating and printing custom graphpaper.
It supports square and non-square grids with major and minor divisions.
You can specify either number of major/minor divisions or the physical dimensions of each grid cell in 1/72th of an inch increments.
It is great for using a whole piece of paper to sketch out a project. It also has defaults for typical home improvement scaled projects and also for knitting projects where a non-square grid comes in handy.