These are very addictive! I tried the comic strip generator- http://www.comicstripgenerator.com/- and made some signs for special collections in my library. If this site is accessible from school, I am planning to show my aide how to use it. She enjoys making signs and posters for the library.
I have used ImageChef- http://www.imagechef.com/ - before, but haven't explored all the possibilities. I've used the Word Mosaic in the past, but this time I tried the Visual Poetry tool and made a picture for my blog (down at the bottom on the right). Then I tried the poetry blender and made a welcome animation for my library webpage. We use eChalk, and I was able to copy and embed the HTML in my webpage editor, and the animation looked great in the preview. When I go to the actual webpage, however, I don't see the animation, just the HTML text, so I'm going to have to get some help to make this work.
There are so many other options out there. Don't know when I will find the time to play with all of them, but it is nice to have them in my toolkit when a project comes up. I think these would be very motivational for kids, but would also be a big distractor, so maybe they could be used as a reward for finishing other work- like "you are doing a great job on your research, let me show you how to add a cool graphic to your presentation." They would also be fun for teachers, so maybe I can incorporate them as fun breaks when I am teaching other stuff.