I would like to have a visual history of my Tomato bandwidth graphs, so that I can roughly/manually correlate them with some other factors. Tomato can squirrel away the actual data points, but I'd rather not deal with importing it into some visualization tool. For sheer simplicity, a single image per day would be preferable.

I'd like a program that can wake up at say, midnight, take a screenshot of a given webpage (the URL will always be the same), and save that image to a folder, maybe named after the date/time. I'd prefer OS X, but Windows and Linux are fair game too; I use all three. Any suggestions?