When exploring and playing with image generators online I must say that I prefer BeFunky.com - it was easy to sign up to using an email address - unlike Big Huge Lab - as a teacher I felt it was inappropriate to be signing in for educational purposes using a personal Facebook profile. However, it is interesting to see that large puzzles can be made, printed and ordered on the website (Big Huge Lab) and could be very interesting starters or plenaries for the classroom (it is also nice to know that resources can be tailor-made for subjects/topics like a puzzle or large classroom mat). A couple years back I watched a lesson on teacher TV - (I think it was an English class reading Shakespeare) where the mat in the room was a map of Europe and the students stood in the different countries where the characters in the book were from- an engaging and active learning classroom experience!
I found the Cartoon Generator very simple and limiting. I can see it being used as a quirky ice breaker and feel that it would be of a the benefit in subjects such as PD/Health (cartoon task), Drama (mime/commedia dell'arte unit) or even in English.
Image generator was also quite simple and basic - something to create a front cover or funny picture for entertainment value and not much else.
In BeFunky, I had more control over my creations, I also didn't have to order anything in particular/sign up with a Facebook account. It was also interesting to see that when changing/modifying/improving pictures/images - there is a beautify button as well as a wrinkle remover!!! Great to keep in mind :)