This week I really like two different comic strip generator sites for kids. Comics are a great tool for the classroom as they encourage students (especially boys ages 10 - 14!) to WRITE. Making comic strips can be a good way to get those normally reluctant writers to get creative and express themselves. Working on the elements of fiction? Comics are a fun context that students can identify with and that are probably familiar to them.
Make Beliefs Comix is a free site that does not require a login (no student sign up!) to use. This one is good for the younger crowd or students who need a bit more inspiration since the characters are already pre-drawn, and it's a simple drag-and-drop to insert those pre-made characters into the frames and add your text.
I also like ComicMaster. Though there is the option to create a login, a login is not required to make free comics using all kinds of creative tools. The more advanced comic creator or older students may enjoy the freedom that this generator provides. Once the comic is created, they can print them.
For both of these sites, I'd recommend students spending some time playing with the generators to get a feel for the tools and their capabilities, as well as some time to pre-write and plan their comics on paper first. By then, students would be comfortable with the tool and have a clear plan of what they wanted to create in order to complete their comics in one sitting.