Bill Zimmerman’s Make Beliefs Comix site is one that I suggest teachers use if they are interested in having their students create webcomics. It is a site that is easy to use, is cute and kids get it right away. Bill just added a handful of new characters to the site and also added objects to be used in the comics.
And I want to point out that the site is also a good resource for Second Language or ELL instruction, as you can compose in English, Spanish, Portuguese, Latin, German or French. Pretty neat.
Peace (in the strip),
Kevin