[Update: the white text no longer helps Oxcyon — they’re not even the top hit for their own company name any more.]
I’ve just stumbled across the most extreme white-text example I’ve ever seen, and it belongs not to a porn site but to an enterprise software vendor. Check it out:
Scroll to the bottom of the visible text and then start highlighting with your mouse to bring into view screen after screen of white-text key words and phrases custom-designed to get the attention of Google and other search engines. Or, if you prefer, just bring the site up in lynx.
I guess this kind of thing still works. I tried a Google search for “stellent taxonomy support“, and Oxcyon — not Stellent (a competitor) — was the first hit.