A good picture is worth more than a thousand words. In problem solving and communicating, pictures really can clear things up. Pictures are often better at abstracting and capturing a general idea, and our brains are very well optimized at recognizing and categorizing what we see. If you can see it is more "real" and substantial than just talk or words.
A great book on using very simple pictures in problem solving and communicating is "The Back of the Napkin". I recently finished the book, it's a fun read and a good reference when creating pictures for presentations. Author Dan Roam recently did a talk at Google explaining some of the ideas in the book. The presentation has some great examples, including explaining why Microsoft wanting to buy Yahoo actually was a good idea. Roam is a great presenter, if you are interested in using pictures more, watch the presentation!