Our method is pretty simple. We already own a Celeb fitness forum which is mostly discussion based and media driven (pictures & videos etc). Thus, we thought it was a "no-brainer" to lobby our own image-hosting service. 🙂 Luckily, I was aware of Chevereto cms and it's been around for years. It's a cool product with many features and a hardcore on-going customer support.
What we're doing with our forum at the moment is gradually building an internal program whereby any 3rd party image-host links are converted to our own chevereto cms links.
That's our route to marketing our own image-hosting service. We're basically using our own community to lobby our own image hosting service. It's still in it's infancy and I am kicking myself for not doing this earlier.