Tracking Your Buddy List

(Business 2.0 Magazine) -- While traveling in Europe earlier this year, Nokia (Charts) product manager Jyri Engestrom missed his friends and family - and wished for a way to find out where they were without calling them all.

That led him to quit the Finnish phone giant and create Jaiku with $25,000 of his and co-founder Petteri Koponen's money. The Helsinki startup's free mobile application is a buddy list with a twist: By using information from cell-phone towers and the input of other users who once stood where you are, Jaiku figures out your exact location and broadcasts it to your buddies, and vice versa.

Jaiku's service is a mere three months old but has already garnered nearly 10,000 users and is winning praise from early adopters and analysts. "This is a very cool technology," says Julie Ask, a senior analyst at Jupiter-Research. "It has the potential to take off."

Based on mobile ad network AdMob's pay-per-click prices - 5 cents to $1 - Engestrom conservatively estimates that Jaiku's very targeted location-specific ads will fetch about $1 per click, which could add up to as much as $500,000 in revenue next year.

He still doesn't see friends and family often enough, he says, but "now they know what I'm up to just by glancing at their phones."