I've recently been moving all my personal email over to a new account, and I can't believe how many newsletters and organizations have an unsubscribe link that's simply that, with no way to easily change your email address or sign back up. What a missed opportunity!

Marketers, if I have to specifically go back to your site to find the newsletter signup again, or jump through hoops trying to guess what login I might have used 3 years ago somewhere, I'm a lot less likely to opt in. Make it easy for me!