This website provides fun generators and has a RSS feed. Not all items are appropriate for school use, so I just show students the tools that I really like to use. Here is a link to slideshow that I prepared for staff at Hubert Olson Middle School. In this slideshow, I used about 15 image generators to demonstrate their possible use in the classroom. I added links to where each generator was found. I also linked a few resources for copyright free images on the final slide.
