Ask HN: Resources for monetizing email lists around community?

HN - I have several sites where I have collected emails but done nothing with them. I also have a few communities I'm incubating where collecting email addresses is really cheap.

What are "best of" training resources / vignettes, etc, that you could point me to where I can learn some best practices on how to MONETIZE these lists?

One thing I'm not really interested in is a paid newsletter. I don't think I could get it in me to publish something 1-3 times a week to generate the value required. But feel free to change my mind!

Also, I'd love some benchmarks on revenue per subscriber to understand value.

Have at it HN hivemind!