From Wikipedia: "Skype was founded in 2003 by Janus Friis from Denmark and Niklas Zennström from Sweden. The Skype software was developed by Estonians Ahti Heinla, Priit Kasesalu, and Jaan Tallinn, who together with Friis and Zennström were also behind the peer-to-peer file sharing software Kazaa."

All three countries lay claim to Skype, but the Skype main development centre (ie the juicy jobs) is (was? not sure after the sale to Microsoft) in Tallinn, and while Friis and Zennström met in Denmark, they'd moved to Amsterdam by the time they started work on Kazaa (from WP on Janus Friis).