How does Hilary Erickson's email segmentation method outperform traditional approaches?

My email “segmentation” is really about letting you tell me what you want. Instead of one big list, I offer simple, self-serve links and pages where you can choose things like:

1. Only weekly newsletter (via the “Too Much Email?” option)
2. No MomHacker parenting emails
3. Staying on lists for pregnancy, money, cleaning, blogging, etc.

Compared with traditional “spray everyone” approaches, that:

1. Cuts down inbox overload
2. Increases open and click rates
3. Keeps trust high because you only get what you’ve asked for

What kind of emails or audience are you thinking about segmenting?