There's a sizeable portion of the population for whom RSS would be perfect, but they don't know it exists, and if you tried to get them into it, would be baffle

There's a sizeable portion of the population for whom RSS would be perfect, but they don't know it exists, and if you tried to get them into it, would be baffled by the complete lack of interface (remember when Firefox would show an RSS icon near the URL when a site had an RSS link in the header?) A newsletter is useless to you, but a lot of people like them. I agree that popups aren't the way to push it, though. A simple newsletter link in the header of the site is more than good enough. I don't care how good the "conversion" rate is, I don't like harassing people who are just visiting my site for the first time.