Mike Rankin in IndesignSecrets.com
Ever want to draw a series of concentric shapes? It may not be obvious how to do it, but really they’re just a few clicks away.
Click on the W or H to highlight the width or height. Then hold the Option/Alt key and press the up arrow as many times as you like. Each time you press the arrow, you make a copy that is exactly 1 cm larger in diameter.