“Create presentations that have more in common with a documentary film than an overhead transparency. ”
Source: Carmine Gallo, “Rethinking the presentation.” BusinessWeek. April 4, 2008.
Slides with pictures are remembered better (the picture superiority effect) and are also more efficiently processed in working memory than slides with lots of text.
Contributors to Stock Exchange license their images but the terms are usually quite liberal, especially for presentations. Flickr lets its users designate their photos as Creative Commons and in fact, many of my own photos are free for you to use in your presentations.
Visit my Flickr page and feel free to download and use any of my images in your own presentations. Enjoy!