Hmmmm, now that explains a great deal about the increasing number of promotional items i'm now seeing.
Besides changing my settings, i'm going to have to consider un-liking some services.
Facebook users, you may not have realized it at the time, but by ‘liking’ any particular Page on the social network, you volunteered to act as a digital billboard for that Page’s ads.
My colleague Anthony Wing Kosner takes Facebook to town for “promoting stories you’ve never seen to all of your friends.” Kosner’s post was inspired by Craig Condon, a user who noticed that Facebook lets Pages that you have liked tell your friends about “Related Posts” on your behalf, even if you’ve never interacted with those posts. So if I liked a band, for example, that band could run an ad in my friends’ news feeds saying “Kashmir Hill likes Explosions in the Sky. They are playing in your town on such and such a date. You should buy a ticket!”Ads May Be Appearing On Your Facebook Friends News Feeds Because You 'Liked' Something [forbes.com]
So if I don’t want these bands to be able to run ads targeted at my friends in their news feeds, I need to either unlike them or change my privacy settings so that only I see these likes or only the subset of Facebook users I want seeing ads see these likes: