What is Cheat Sheet?

Cheat Sheet are quick reference guide as reference cards.

In more general usage, a "cheat sheet" is any short (one or two page) reference to terms, commands, or symbols where the user is expected to understand the use of such terms etc but not necessarily to have memorized all of them. Many computer applications, for example, have cheat sheets included in their documentation which list keystrokes or menu commands needed to achieve specific tasks to save the user the effort of digging through an entire manual to find the keystroke needed to, for example, move between two windows.

Usage of Cheat Sheet -->
1. To capture Maths formulas
2. To capture syntax of particular Software or package or Computer Language.
and much more..

Please check out : http://cheatsheet.absolut-e.com , You can create your own cheat sheet or reference card. Still on development. We will be releasing soon with OpenId and on that time you can create your own CheatSheet and create PDF.
Feel free to provide your suggestion on this application http://cheatsheet.absolut-e.com