Best images
A picture can be worth much more than a thousand words, if it communicates the beauty of science and engineering, as well as their concepts. Chapter 12 of Explaining Research shows how to produce effective research photography, either yourself or working with a professional photographer.
These contests and galleries exemplify the best in scientific imagery:
Also, see this Felice Frankel 2006 illustrated talk at the New York Academy of Sciences for an excellent discourse on the role of aesthetics in science imaging.