Hi, Roy ..
I can't say I've made any significant income from the Amazon AP over the years ... but then again, I've not really gone out of my way to incorporate their links.
That will change, however, when I relaunch ... hopefully soon, as the ability to promote reference material related to content, passively, makes it worthwhile (IMHO).
And that's not even taking into consideration all the other product types they offer.
If nothing else, the broad range of promotable products that directly/indirectly compliment(s) almost any topic, easily weaved into site content, makes it a passive promotion plus for any webmaster.
Regards,
Mike "the major brand association doesn't hurt, either" Merz