I think it will be convenient for the #467582: Change the settings page to add a field with the date of the file request.
Great idea but it could works only for file based verifications.
Date of the file request? Could you please elaborate as to what you mean?
The main purpose is to aggregate statistics about using validation by search engines.
The idea is add new field (for ex. requested) as unix timestamp and update it when file requested from outside in site_verify_output() function.
But maybe better to provide a trigger|hook or just menu_alter() in custom module.
Opposite opinion - using web-server logs to count this statistics
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