I like the idea.
I had a related idea: a "calling card" function, to indicate you have an interest in a particular grave.
Suppose Jenny wants to make contact with other descendants of her great-great-great-grandmother. She could try sending a message to the photographer and/or transcriber, but chances are they're not related to the deceased person. Many prolific photographers and transcribers on BG have worked on tens of thousands of graves, and are only related to a tiny fraction of them, if any. So Jenny has no easy way of contacting her distant cousins. The most she could do would be to leave a message in the Personal History section of the record, and that's not ideal. For one thing, messages like that are not personal histories - it's not what BG intended that field to be used for. For another thing, Jenny would have to include her email address. She might be OK with giving it to her distant cousins, but she doesn't want the entire world to see it. In contrast, clicking on a "calling card" button would let distant cousins know that Jenny has an interest in this grave, and it would give them a way to contact her if they wish.
More details here: http://community.billiongraves.com/2747/enhancement-idea-leave-calling-card-graves-are-interested