Spotify -
And in their Jobs section they say "At Spotify work is about creating easy intuitive media distribution and advertising services. We do that by solving hard computer science problems as well as making the services easy-to-use. Our projects include everything from creating algorithms that make the advertising relevant to users and valuable to marketers, to designing a new interesting front page for our website. The core of the company lies in engineering – we're a data driven company. Our engineers work on problems in a number of areas, including distributed systems, information retrieval, algorithms, UI and scalability issues when dealing with huge amounts of data and a rapidly growing user base."
Not enough info there to figure out what they are going to do to separate themselves from the pack ... so we'll have to wait and see. In the meantime, there are some flickr images to browse and ponder: Spotify at flickr