Here's a mini rant about Amazon.com: Apparently, user accounts there are identified by some combination of email address and password. That is, you can login with the same email address, give three different passwords, and get three different sets of user data. Different wishlists, different shopping carts, the works.
Enter me: I've changed my password so many times at so many places that I've now got a dozen or so possibilities to try if I happen to forget what I'm using at a particular place.
I do this at Amazon with an ancient password and rediscover an even more ancient wishlist I'd started from back before they bought out CDNow. Kudos to them for migrating my list, which provided some nostalgia, but now I have to try to figure out which password takes me to more current stuff. I try another one, and I get a slightly newer abandoned wishlist of mine. Wow. Did I actually want some of that crap? Anyway, try again with a different password or two and I finally get to what I want.
Talk about surprising the user...