It appears as though at least a couple of airlines have changed their policies regarding bonus miles for booking your itinerary from their website. Delta used to advertise on their homepage that you would get 500 bonus miles for flying on tickets purchased at delta.com. However, this text no longer appears on their home page, and I have been unable to find evidence of any such bonus elsewhere on their site.

Likewise, US Airways used to advertise 500 bonus miles for flying on tickets purchased at usairways.com, and I can no longer find that bonus being advertised on their site either. Our Frequent Flyer Programs page has been updated to reflect these apparent changes.