Word of mouth led me to various knowledge of two sites that allow you to listen to music on demand, or directly from the site in question and because I find the very nice place you here the two links explaining briefly the difference between the two:
http://www.deezer.com/ : This site allows you to enter an author TUUUTTA and listen to recordings, selecting the album, creating play list at will or to tune in to some stations that broadcast a variety of musical genres.
http://www.lastfm.it/music This however allows you to download a small program that opens directly on the computer where you can type the name of an artist to listen to artists similar to that required, or to choose the kind Music to listen to everything that's available on that genre. The flaw of this program is that you can not choose what to listen to and you can not listen to the songs when you want it, but I really like because it allows you to learn new artists and, above all, for me being lazy is a godsend, you put the songs without having to select them at random!
I hope someone likes these sites as they liked me!
Enjoy!