On: Ads in Gmail displayed as normal emails?

[6ren]

They are a counter-example: you are not the customer (you aren't paying for it), but you also are not the product.

[jpadkins → 6ren]

Actually, I think you are the product for free software. Think in terms of non-monetary rewards. Developers get satisfaction and sense of achievement from the number of users using their software. So your usage is actually the 'product'.