I'm sure this goes completely against the TOS, but what if I iframed a high paying MFA on my high traffic site?
yupe right, i frame is not search engine friendly. better use php include function. I think there was a time when Google adsense give the their adsense code in for iframe use.
erm im pretty sure you can only use php include to include php pages... so its not gonna be that useful if the page is html.
If you use the php include then the included file will be part of the main file... so the robot will display ads base on the page content not base on the included file. Unlike iframe robot will base the ads to display on th econtent of the iframed file.