I know where you are

"What are your friends buying?" That's the question asked by Blippy, a social network that automatically publishes everything a user buys with a credit card for all to see. Launched in December, Blippy now has more than 10,000 users who share information on about $250,000 worth of purchases a day, from books to beds. "People are curious about other people's buying habits and choices," Ron Conway, a professional investor who has backed Blippy, told the Financial Times.

Another new set of internet services allows users to "check in" to locations with their mobile phone, telling everyone on the Web of their whereabouts. They have names like Gowalla and Foursquare, which now has 450,000 users.

Foursquare has been joined online by Plancast, a service which allows users to share their travel plans. The thinking behind the new services is that by knowing where one's friends are (as Foursquare makes possible) or knowing where they are travelling to (as happens on Plancast) people can connect with each other at cafes, clubs, concerts and airports.