I have been doing research on wordless picturebooks for my Reading Teacher Column for Fall 2014. Another of my favorites is Unspoken by Henry Cole. In this powerful story about a runaway slave hiding from soldiers along the underground railroad, Cole features black and white charcoal sketches to render the visual narrative. The facial expressions and eyes add a depth of emotion to the narrative. This is a perfect example of how wordless picturebooks are not for young readers alone.
Here is a video clip with Henry Cole reading (discussing) his wordless picturebook: http://www.youtube.com/watch?v=voL_dToHjUU