Displaying your findings : A practical guide for creating figures, posters, and presentations
A student's guide to presentations: Making your presentation count
The Wall Street journal guide to information graphics: The do's and don'ts of presenting data, facts, and figures

The same copyright issues that pertain to written property must be observed for images. While many of these databases provide freely usable images, please check the copyright information and/or licensing restrictions carefully before using the images for public consumption. Cite or attribute what you do use appropriately.
NOTE: The Advanced Search features of Google, Flickr and Yahoo image searches have a check-off button allowing you to search for re-usable images.