Icon Bug is a collection of more than 10,000 icons and pieces of clip art that can be downloaded and re-used for free. The Icon Bug search engine allows you to search by keyword, browse popular icon categories, and refine searches according to icon size. Registered users can upload their own icons to contribute to the gallery.
Applications for Education
If your students need some clip art icons to use in presentations, in blog posts, or in another medium Icon Bug could be a good place to find the icons they need. Just remind students that even though the icons are free to use, most of the icon contributors do request attribution.
H/T to Steven Anderson for sharing this on Twitter.