The quickest way to do this is to use HTML Tidy. You can download it here. When you attempt to "Tidy" a page, it will give you plenty of hints about accessibility. If you're careful, you could just write a spider for your site and call tidy with backticks.

Side note: I used to do some programming for Special Olympics and I'm glad to see that there are others out there who care about this issue :)

Cheers,
Ovid

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