Think about it.. Same goes for you being with someone whose birthday pictures you're looking at and you can provide a context to them. Gifting is an area you can charge advertisers for. Think fashion!!! We take pictures all the time!! If you could provide the context to where the pictures were taken, the store it was taken in, and how there is a discount going on in that store, it would be amazing! Use the context of the photos, for instance, as 'subscriptions' to these contexts.
To elaborate, think of this scenario. I took a photo at H&M on Regent Street in London and then at Next further along the road. Since I took at photo at H&M, you can 'subscribe' me into H&M offers, etc. And same goes for Next. So when there are offers, an ongoing sale or either of the brands just looking to reach out to customers, you could be the conduit for them!!!!!!!!! THAT IS WORTH A LOOOOOTTT OF MONEY!
If you're not doing it, I WILL! :D :D