To find out the friends of Joes friends that are not already his friends, Cypher looks like:

Query

START joe=node:node_auto_index(name = "Joe")
MATCH joe-[:knows]->friend-[:knows]->friend_of_friend, joe-[r?:knows]->friend_of_friend
WHERE r IS NULL
RETURN friend_of_friend.name, COUNT(*)
ORDER BY COUNT(*) DESC, friend_of_friend.name

The list of Friends-of-friends order by the number of connections to them, secondly by their name.