Gridzzly is a beautifully simple tool for anyone who uses grid, graph, or ruled paper. The webapp lets you fine-tune the pattern you need for printing. Just choose the shape (dots, lines, squares ...

This online graph paper generator will allow you to make your own graph paper, and even customize it to suit your needs. With things like multi-weight lines, and polar graphs and much more.

Print out in-a-pinch graph paper or rulers. Sometimes it's just easier to write or sketch out your thoughts when there's guidelines on your paper, as you may remember from grade school.