Dopplr

Dopplr is a free social networking service, launched in 2007, that allows users to create itineraries of their travel plans and spot correlations with their contacts’ travel plans in order to arrange meetings at any point on their journey.
Additional features include allowing the user to calculate the carbon footprint their journeys have produced. New features are being added continuously adding to the benefits of travellers.

The site is named after Christian Doppler, discoverer of the Doppler effect. The company is based in the Old Street area of London.

In 2007, Jimmy Wales, the founder of Wikipedia, described it in an interview with The New York Times as his favorite non-wiki website.

A survey carried out in early 2008 on influential technology figures by the Guardian Media Group named Dopplr as a company to watch out for.