Janee Aronoff has a tutorial on her site that creates a grid to mark the center point of the canvas by percent. What's really cool is she made it so that it has a shortcut key.

http://www.myjanee.com/tuts/centeract/centeract.htm

Of course, I know I can do this my changing the ruler and grid defaults, but having it available as one keystroke would be grand!

Patti
P.S. Just beginning to tap the possibilities of Elements 2 with Richard's book. Look forward to learning more.