I just read/skimmed Naughty or Nice? CSS Background Images [http://24ways.org/]. Now this is an old post (2005), and I don't remember how I stumbled on it, but the post makes a good point - don't stick in CSS what should be delivered via content.
I always try (with mixed success, I admit - it depends on how much control I have) to load my pages in lynx or some other text based browser to make sure I can still get around. I increasingly find sites that are not navigable sans full-graphical-browser tricks.