I have thought about a problem that is somewhat related: You want to communicate with an entity that you do not personally know or have on your contacts list, b

I have thought about a problem that is somewhat related: You want to communicate with an entity that you do not personally know or have on your contacts list, but you share some semantic aspect with this person - e.g. same commute to work, or same day care center for your kids and theirs. The solutions I'd thought of for this problem was to employ an entity that exists at a higher hierarchical level - say the mobile phone company, that can 'see' the common aspect and can allow you to contact this person on a need-to-contact basis. I call this 'semantic social links' for lack of a better term. The idea is slippery though because it must be balanced with privacy properly. The problem you have described is different because an actual meeting has occurred between the two parties, and yet perhaps it has a simple (orthodox?) solution -- giving/taking business cards. You are asking for some way of digitally bookmarking this business card. -Suhas