[dkokelley]

I would start by just offering the service and gaining traction. I think trading the service offering for occasional or integrated marketing emails is acceptable for most users.

Over time, you will build your user base/email list. You may be able to identify certain segments within that list that share a particular interest. Now you know what these users like, and have explicit permission to market to them. Use this service as a platform to engage your users and discover other ways that you can add value to their lives in such a way that they are happy to pay for it.

In summary:

1: Build the service, get users

2: Where possible, segment those users by interest

3: Based on the major interests, build and/or sell other products that your users will pay for