Twitter is a fabulous resource for images.
I use images a lot to hook classes in and write about it in my book.
I wanted to signpost some Twitter places where you could find images instantly and that may work as stimulus for your writing, History or Drama work.
Hope this brief list helps:
I’d also like to point you to this fabulous blog by @ictevangelist for some brilliant apps, many of which use image as a starting point.
It’s here: http://educationevangelist.com/ipad/an-ipad-toolkit-29-apps-that-promote-good-learning/