Thanks for the links; I'll definitely be reading through those later (as this field is very interesting to me)! I think I may have confused matters somewhat by

Thanks for the links; I'll definitely be reading through those later (as this field is very interesting to me)! I think I may have confused matters somewhat by comparing directly to a 'Like', which is more like a 0-1 rating system, rather than to a combination of Liking and Sharing. How far it goes towards each of those is something I'm experimenting with :) > Here is a fun one. If a person likes 2 different photos, we can say that is a connection between them of strength 1/log(# photos liked by that person). The total connection between any two photos is the sum of the connections. From each photo we can now find other photos that are in some sense likely to be liked by people who like the first. People enjoy following connections like these. I can't wait until I have more data to play with and I can start experimenting with ways of connecting photos like you say; I've not often had the chance to try out some of these ideas due to the limited size of datasets I've had in the past.