I originally built this as a b-day present for my wife, and she liked it so much that I decided to turn it into a public service. And I'll be happy if it's just that.
But we do have a model to generate (modest) revenue, which hopefully will cover the (again, modest) costs: At the end, when the recipient has seen all the letters, s/he can order an actual, physical book with all the text. It's printed on-demand, and we're make a bit of $$$ over what the publisher charges.
Amazing! I could not realize this 'off-line' business model aspect of the site!
But must work as all other online-to-offline modeled businesses. You can contact Springwise.com maybe they'll put in their feed, they like these on/off combinations.
The 'off-line' model is actually quite common in the wedding world. I know a person running a wedding website hosting (planning, photos, invitations, etc) site where the couple can get everything on a CD once the wedding is over for a small charge.
Useful to keep these additional models in mind when thinking of a new business idea
