Spotify are hoping to use the music you listen to in order to target adverts.
It could sort-of work: If you like Robin Beck, you might want to buy Diet Coke.
But it's not really this simple, is it?
The Spotify founder and CEO, Daniel Ek, explained the thinking behind personalised advertising.
He said: "There's a simple principle – we are trying to make a better advertising solution. We are showing that, around the data, there are things that matter. For instance, combining demography with music taste, we can group you with other users. We can then predict whether you like Audi better than BMW and then serve you advertising from either of them.
"There are certain brands that want to be associated with things that are cheerful and others with classical music and there's a lot of things we can do in this area."
Well, yes: if an advertiser wants to advertise to people who listen to classical music, that would be easy. It's not quite the same as working out whether it's better to serve a Central Office Of Information warning about Swine Flu to an 80s Matchbox B-Line Disaster listener or a Katy Perry fan?