I recently discovered some online radio stations that play non-stop music (mostly western) over the internet. The one I am currently listening is AOL Radio. There are different stations for different genres of music like Jazz, Western Classical, Country, Rock, Hip-Hop, Pop, Dance, World Music, etc. And under each category, there are various sub-categories. My current favorites are Jazz (Martini Lounge, Romantic Jazz), Western Classical and Country. Each station plays non-stop music without any audio advertisements. Since it is a radio station, you cannot choose the song you want or fast-forward songs. The songs are being played in different stations and you can tune in to the station you want. It is like the WorldSpace Radio online. It doesn't have any indian classical music stations, but it covers a wide variety of different genres.
I checked my internet usage logs and found that listening to about 1 hour of music will take up 45 to 50 MB of your bandwidth.
Let me know if you are aware of other good free online radio stations.