This Is What I Get For Cooperating With Capitalism
I registered at http://www.gianteagle.com in order to sign up for the "Apples for the Students" program. Instead of collecting receipts to give to the school, it's associated with the Advantage card--you just show the card when you shop and their automated systems give the appropriate amount to the school you designate.
I discovered that registering gives access to at least some of the data they have on you. In particular, you can get a list of all the products you've ever bought from Giant Eagle.