Here's a crazy idea. What if someone created a web-based email application that removed all expectations of privacy? In other words, you just email as you normally would except that it's all out there in the public; exposed. People using this service would most likely self-edit, I'll admit that.
Nevertheless, it would be interesting. You'd get to know people by tuning in to their communications with others and you might tag or mark certain emails as favorites, etc. It'd be like blogging, dating, message boards, and more all rolled into one without any extra effort because all you're doing is email. Wacky.