With UbuntuOne closing down, Emusic quitting al suppport for their linuxclient, I have but one question:
Where can I spent my Euros to buy legal music. On Ubuntu?
You can also use 7digital. Ubuntu One was using 7digital as music provider, but with different agreements for territorial limitations. If 7digital is available for your country, you may even find many more musics available for purchase.
7digital for Nederlands : http://nl.7digital.com/
You can try Spotify, you can install it from its website at this page. It has two plan types: free, that doesn't allow to download music, and has a lot of ads, and premium, that hasn't any ad, and allows you to download music on your computer, not as MP3, but in a special format, recognized only by Spotify Player.
it's simple with Google as you know or not they launched Google Music service not so long ago and there's extension also available for Google Chrome and Chromium browsers alike, where you can listen and buy music of your taste.
The Amazon MP3 store is available in some countries:
United States, United Kingdom, Germany, France, Austria, Switzerland, Japan, Italy, Spain
They let you both stream the songs and download the MP3 files using a web browser. If you want to download multiple files at one time you have to install their client, though.