Dopplr

Dopplr was a social networking service for frequent international travelers. Members shared personal and business travel plans privately with their networks, exchanged tips on places to stay, eat, and explore in cities worldwide, and discovered when their travels coincided with connections. Dopplr presented this collective intelligence — the travel patterns, tips, and advice of the world's most frequent travelers — as a Social Atlas. Acquired by Nokia in 2009, the service has since been discontinued.