This script converts dates in the following formats to the ISO 8601 YYYY-MM-DD format:
Sites whose content is loaded after the page is loaded (and therefore after the userscript is run) can have their dates fixed via the ISO 8601 Dates menu command.
Note: this script does not run on any sites by default. Wildcards for offending sites should be added to the userscript engine's list of includes e.g. to add www.example.com to Greasemonkey: Tools -> Greasemonkey -> Manage User Scripts... -> ISO 8601 Dates -> Preferences -> User Settings -> Included Pages -> Add -> http://www.example.com/*.