Story Top is a good web-based tool for creating digital stories and comics. Story Top features an easy-to-use drag and drop tool for creating your story. To use Story Top simply select your background, characters, and text bubbles from the menu and drag them into your story box. After selecting the basic story elements you can then add additional elements like plants, animals, and vehicles. When your story is complete you can save it in your Story Top account or send it to friend. You can also share your story with a group of other Story Top users.

Applications for Education
Story Top is a good tool for getting students online and creating stories quickly. The user interface is easy to use and offers just enough features to allow students to create digital comics that they can be proud of.

Here are some related resources that may be of interest to you:
7 Resources for Creating Cartoons and Comics
Comiqs - Create Comics to Play as a Slideshow
Make Beliefs - Multilingual Comic Creation