There's a discussion going on at the Hero Arts Flickr group about design principles and elements, so I thought I'd share my own favorite online resources here as well.
A nice reference poster for design principles to download and print.
A nice reference poster for color theory to download and print.
A nice reference poster for design elements to download and print.
Here are actual drawings that specifically illustrate these verbal definitions.
A great slideshow that provides detailed illustrations of design elements and principles.
Just for fun, an art game site.
I think this video is about the most exciting thing I've seen in awhile! It visualizes Richard Saul Wurman’s LATCH system of organization. Very cool.
Thanks for stopping and have a blessed day!