When thinking more about personalizing (might be obvious, I don't know):
Bear in mind, though, I am the kinda person that likes clean and minimal and don't really like having to manage online profiles on a gazillion sites.
But say, next to the articles you send out, perhaps have a few tags that categorizes the article. For instance, if it's related to Europe, US, Global, automobile, IT, woodcrafting. Make the tags clickable (unique ID per user in the mail) -- a click on it means "yay, gimme more". How to undo a click, well, I dunno... Some down-arrow like at HN?
