We are always looking for new ways to teach and review with our students. I recently took a visit to ToonDoo and tried my handiwork at making one. I have blogged and posted it in the Maze, but wondered if anyone had any views on this tool or others they like. There is a definite learning curve, at least for me!
While not a 2.0 product, I like http://www.mycomicbookcreator.com/ for creating comics. I purchased the product so I could use all features, but there is a trial version.
I use Makebeliefscomix with my intermediate level ESL adult students (and High Beginning ESL in the past) to give them an opportunity to practice vocabulary and grammatical structures they've been introduced to in class. It's quite easy to use and a lot of fun as well. You can see some examples at http://esl.adultinstruction.org/ComicStripProject.htm
The two creators previously mentioned are great tools. For more practical stuff and even more exciting cartoon materials, we had a great thread on EFL Classroom 2.0 Unfortunately you need a short sign in but the thread is worth it. Search under comics. We also have folders of resources for teachers, this is the present shared folder for members on comics.....
Grammarman comics in our video player is a great site also....I'll look up the url.
If you have a Mac, it's hard to beat Comic Life. It's very easy to use. My students had a great time thinking up a story line, using their classmates while staging photos, then converting them to comics. We were able to print them, as well as, export them as jpegs to put on our school websites.