It has become a sort of Christmas tradition of mine to send out a Christmas greeting to everyone I've met from around the world. Usually, a lot of emails bounce because either email accounts have been closed or their inboxes full (hopefully of Christmas & New Year messages like this one), but most get through, and it gives me great satisfaction to think that somewhere on the other parts of the world, a friend or family is reading my holiday greetings!
Sometimes a few reply with the fondest greetings and some even with photos. That's the coolest thing about it really: that even though we have not seen each other in years, and even if it is just once a year, we remember and smile for the memories. :D