My Chumby now displays random images off of 4chan's /b/. I ended up using a pre-made image displaying widget and then writing my own spider/parser/XML output engine on www.lulzlunch.com. Anyone can use it by enabling the PhotoFrame widget with the URL set to "http://www.lulzlunch.com/images/b". It now auto updates about once every 12 hours. An automatic resize is in place. I should have a chance to test it on Wednesday.
-Paul

Update: It's been working great for a while. You can even view random images from your browser. There are instructions at http://www.lulzlunch.com/index.py/chumbyinstructions