An ALA preconference focused on using images and visuals to enhance presentations. Instead of slide after slide of text and bulleted lists, visuals are memorable ways to get your message across. The conference materials are accessible here. I've also saved two of their presentations and a list of related resources to the Reference drive under Instructional Materials. Look for these files:
Power of Image - ALA conference presentation
Get the Picture - ALA conference presentation
Resources for effective presentations - ALA conference presentation
Although the Power Points utilize the presenters' philosophy to tell a story using images, not text, you can still gain a lot of valuable information from their slides (and the notes that are visible if you do not view it as a slideshow).
The list of resources includes links for finding free creative commons images. I've also tagged some sites for this purpose which you can access at http://delicious.com/bookchic831/images.