Not sure what sub-forum to post this in, so mods, please move the thread as necessary.

The other night I used the free "Shazam" app on my Android smartphone to identify a song that was playing. I don't have any Shazam account, don't log in to Google, etc.

Today, when I went to Amazon using Firefox on my Linux box, and was logged in to my Amazon account to check on a recent order, there was a "You might be interested in this" link on the Amazon webpage to the exact song I had previously identified using Shazam on my cellphone.

What mechanism would they have used to target this advertisement at me? On my Linux box, I use NoScript, AdBlock+, Ghostery, and BetterPrivacy, all locked down to really tight levels (not that I think this has anything to do with my Linux box). On the cellphone, no specific protections are present. But I wasn't expecting a jump from my Android cellphone to a web browser on my Linux computer. I have nothing "joining" these two devices together, like a Goggle login or anything like that (well, obviously I do, but don't know what it is - that's why I'm asking here!)

Any ideas about how this "link" was accomplished to target a specific ad at me across quite different devices?

It could be coincidence? If the song is being played on the radio or television then being a suggestion on Amazon would be another part of the advertising campaign. If you like that kind of music and have bought songs or albums from the band before then it's even more likely that you'll have it suggested if it has just come out.
Assuming they did somehow follow you then if you used WiFi at home to connect with your phone they could, in theory, target by IP address.
Otherwise you're missing something like having let the app access your Amazon account or linking your Google account to your Amazon account in some way.
Which of the above is the most likely is something only you know and something that you could test by, for example, identifying a song that's not of a genre you usually listen to, one that's not a current release, or whatever it is that could have led to this being a coincidence.

Not on the radio or TV - it was at my wifes hockey game. One of the standard songs they have burned on the CD they play during breaks in the games. It wasn't even something I'm terribly interested in - I just thought I recognized the voice/style and wanted to know who the group was. Turned out to be "Clocks" by Coldplay. I think I might have bought "The Scientist" by Coldplay from Amazon MP3 several years ago (don't know why though, not really my style of music, which is classical piano). These two Coldplay songs were released back in 2002 - same album it turns out.

Do you, perhaps, link your google account to your Amazon one (I know you can Tweet purchases and I think you can Google+ them)? Is your browser logged into your google account by default when you open it?
It could still be a coincidence though, but an odd one I grant you

I have a Google account. It was required to set up one with my Android phone. I have never used it and never logged in to it. I have never logged in to Google from any computer, for any reason. As a matter of fact, Goggle is specifically blocked from running scripts or setting cookies. On my computers that is. On the Android phone, since I have taken no specific countermeasures, Google is allowed to set cookies and run Javascript (but only on the Android phone). I use Dolphin as my web browser on the Android phone. For every setting available, Shazam does not have any permissions to do anything on my phone. Of course, there are things that they probably do in the background without your permission. Like - "Link something you identified with Shazam to your Amazon account". How they actually accomplished that feat is intriguing to me. Not that I am terribly bothered by it - our privacy is invaded all the time - I'm just curious by what mechanism they accomplished it.

This article may help explain how this stuff works.

http://www.allaboutcookies.org/ad-serving/

Finding a useful-looking link was difficult. Most of the search strings I tried either wanted to sell me add-blocking stuff or sell me ad-tracking stuff. Finding something about the "how to" was difficult.

The Wall Street Journal has a video here, but I couldn't get it to play.

Beware of Mad(ison Avenue) men bearing "gifts."

...................................

Well,.. if you registered your phone number or email address with Amazon, then it would make sense that Shazam would be able to share that data with amazon. "Hey amazon, 555-1212 checked this song out." or "hey amazon, the phone with the identity you@gmail.com checked out Hangin Tough by NKOTB"

Not really rocket appliances here.

I will not use a "smart phone" (scare quotes), so have no experience there. I do use a locally-stored-object secure browser/computer. Unfortunately those programs uniquely identify this machine. Try it, you may be surprised.

https://panopticlick.eff.org/

Amazon has no idea what my cellphone number is. Shazam has no idea what email address I use for Amazon orders (a "throwaway email address", used for online ordering only - it is not with gmail either).

Well, now I too have some unwanted solicitations from Amazon.

I recently purchased 2 books on splunk from amazon.com
The books arrive, paid for an put to use immediately.

Yesterday, I get a promotion for Jeep-specific after market lighting gadgets.
I have never told amazon I own a Jeep.
My only conclusion is that some "logic" on amazon's portal where I purchased the books read my cookies and concluded
that "splunk" meant exploring caves, not software.

"Now" amazon decided that I must be also interested in
for which I had to explicitly opt-out of.
surf Amazon.com ?
I'll use privacy modes from now on.

Habitual, if you have visited Jeep-related websites, there's a good chance that one of the "marketing" companies out there has recorded that and coordinated it with other information about your browsing habits and sold it on the open market.

This article will give you some hints about how it's done: http://www.openrightsgroup.org/blog/...-and-profiling