What is some of the methods to do a 'knock-down' textured finish to a ceiling or walls?

First "stomp" the mud on with a big brush, then very lightly drag a wide (12-18") mud blade over it.

Here's some more on it: Hometime - How-To - Project Help - Drywall

Instead of the sprayer they suggest, just use a big texture brush that is typically used for textured ceilings that are left not "knocked down".

Thanks, That is probably the way I will do it. I'll be trying a sample of the 'stomp' method as well as a 'roll on' method tomorrow. Wish me luck