Animoto

Animoto - http://animoto.com/
is very simple but offers no real creative control over what you produce. Just throw some photos at it, choose a music track and voila you've created an MTV style video.
A great tool for producing quick videos.
Curriculum idea - Tom Barret says:
"Last year we used our class (y6) digital camera for recording our work in a science investigation, we then gave the children a sheet of thumbnails of these images for their books. An extension of this simple idea would be to produce a quick movie of their science lesson or PE session. Not as an ICT, presentation task but as a simple, yet imaginatively presented, record of the work they have done."