My idea wasn't supposed to address the denial-of-service problem, it was supposed to solve the getting-bogged-down-in-requests problem.
Anyways, despite my ignorance, we have servers whose sole purpose is to process MySQL queries. Yipee. Leaving us with finding a feasible means of allowing this to be publicly accessible without it serving as the base of a denial of service attack. What if we forced queries to run at a really slow speed; in fact, people would have to put in their email addresses so they could be e-mailed the result? And once a limit has been reached for processor capability, the public query terminal would read something like "Sorry, but the query server is too busy now. Try again later."