Jeffrey Zeldman says we should help our clients see the light by showing them how standards help them, not by "selling" them on standards. I agree wholeheartedly, and I think there should be a test suite available that displays this. For instance, maybe at the WASP, you could go to a page where the stylesheet was editable and the client could post text and see how it works. Every nihgt a little cron job could reset everything so it was back to useable, or maybe it would happen more frequently.
"Why?" you ask. Well, I know, as Zeldman says, its probably more productive to show a client the benefits of standards through their own system, but what about the small design firms that need to win a job using their standards knowledge vs. the competitors obliviousness? The CSS display suite would be a great way to give them a leg up.
Consider this filed in the list of projects to work on.