Relationship space: I like your pictures

I like the way Flickr lets you add anyone as a contact, with or without their consent.

'Add a friend', on other services, often limits you to the people you already know. If they have to accept you as a friend in return, then you wouldn't immediately add someone you never met. You would expect them to see your "I would like to add you to my friends list" request with "do i know you?"

Because Flickr has softened this interaction to the equivalent of paying someone a compliment, it has allowed me to 'meet' people from around the world through their photos (which are amazing windows into their worlds) -- AND to stay in contact with them.

Nice touch.