I use them for revision notes for exams, but you can use them for anything really.
You can make them on the Pocketmod website: http://www.pocketmod.com/v2/
But I made a Word template to customise it a bit more.
If you want, you could make these on the reverse side of used paper to recycle it - hooray for green-ness (just make sure it doesn't have anything important on it)
I've entered this in the Pocket-Sized contest so please vote!
(P.S. This is my first Instructable)
Step 1: Making the Template
Simply replace 'Front Cover', 'Page 1' etc. with whatever you want to put in; pictures, text, calendars, or just blank spaces / lines for writing / drawing.