A WikiBadge to warn browsers of the Wiki that the link they are about to click on will take them to Web page that uses MacromediaFlash. See WhatsWrongWithFlash.
I agree that it would be nice to be warned of flash, pdf, java, etc. I'm not quite sure how making a full blown WikiBadge is better than PlainEnglish.
[Probably for the same reason that you said "PlainEnglish" rather than "plain English" ;-) ] touché
A PDF warning (or DOC warning or ...) is not necessary if you are in the habit of looking at the end of the link URL. ;-)
When I'm feeling testy, I hope the FlashAlert badge can point the proud poster of the URL to the WhatsWrongWithFlash page. Perhaps word of how annoying Flash is on a main page will eventually make its way to the site's designer. One can only hope.
See also: ToggleYourFlash