My students are completely hooked on the app Draw Something... little pictionary movies combined with a word scramble.
I've been using it with some of my writing students too - developing an image, providing clues, reading clues... all on a little screen. I save screen shots of the drawings - and we compare ways the words were drawn.
A new version will allow drawings to be saved -
for a little more control of the participants in the same type of game - create your own pool of drawings by using ShowMe or Educreation (iPads - love both for quick assessments of student work - have them take a photo of their work, draw/comment/send or save)
Amazing Pen (ipods/phones/pads) is a little more involved (background color/pen color/switching screens -)