Without providing personal detail, I have had two incidents this week where an email and a separate conversation both resulted in emails the next day from Amazon suggesting that I guy products related to the email and the conversation.
The email was sent to several people, and two of them were Gmail accounts, so I think it is logical to assume that Google is scanning all gmail messages and passing stuff on to Amazon--Google has admitted as much.
The conversation had to be overheard by an iPhone, which is far more creepy. Apple likes to tout their commitment to privacy, but they are apparently still allowing third parties to activate the microphone and listen in to conversations.
There is really no escaping this, and I have very reluctantly come to the conclusion that a solution probably requires Federal legislation. These technology companies appear to have no shame at all about completely destroying personal privacy.