Chogger appears to be a great tool. You can quickly create whatever kind of comic panel you want, with as many or as few panels as you desire. It has the option if importing images or drawing them. And you can layer in different images, placing them in front or behind one another.
We ended up running into a few issues in the 2 classes I used it in: moving an image from the image collection into a panel led to lots of resizing issues that were pretty difficult to overcome. In addition, it seemed that the Chogger server got overloaded with 12 different machines trying to access it from the router. (I grant that the network at my school is not the greatest, but it happened in 2 different classrooms at different times in the day.)
We ended up problem solving by taking a screen-shot of the mostly completed comics, and then cropping them once they were pasted into a Google Doc.
It should be noted that we were using the FREE anonymous version, so perhaps with creating a user account things improve.
I will give it a couple months to see if things improve and try it again before I completely write it off. It is a great concept, and one of the best/easiest comic creators I have come across, if it actually works the way it appears to be designed to.