What about a side-dish as a marketing tool, to get people interested in your main-dish.

This is the approach we are taking with my current start-up. We have a simple entry point, integrating with the apps, and wearables people currently use. But we don't like anything in the market currently for really solving the problem, so while we build out our own hardware, we're building the app, which is a side-dish, but has it's own revenue stream too.

I'm sure there are other businesses that have done this, can anyone give examples of side-dishes that turned into main-dishes?