What is a Music URL and how to set it on your land?

When you have your own land in Second Life, and you have all the rights on that land, you can easily set your own music.
In the pie menu, which you find by right clicking on the land, you will see “About land”, and than under “Media” the “Music URL”.
But what is that?

According the Wikipedia:
Uniform Resource Locator (URL) formerly known as Universal Resource Locator, is a technical, Web-related term used in two distinct meanings:

• In popular usage, including many technical documents, it is a synonym for Uniform Resource Identifier (URI);
• Strictly, the idea of a uniform syntax for global identifiers of network-retrievable documents was the core idea of the World Wide Web. In the early times, these identifiers were variously called "document names", "Web addresses" and "Uniform Resource Locators". These names were misleading, however, because not all identifiers were locators, and even for those that were, this was not their defining characteristic. Nevertheless, by the time the RFC 1630 formally defined the term "URI" as a generic term best suited to the concept, the term "URL" had gained widespread popularity, which has continued to this day
  

In this case the URL is a music URL, which can be found on the Internet, and allows you to choose from a range of music channels, radio channels, or even your own URL.
When you search on the Internet for music URL’s , you will find thousands of addresses, which you can download and put in your music stream on the grid. The only necessity is that you need the right of the land that you own.
You can also read the post on the official Linden blog about “How to” manage the pie menu of your land.
Just download one of next URL’s and put them in your music stream. It should be that simple.

Top 40 pop rock : http://www.977music.com/
Soft smooth jazz : http://www.sky.fm/smoothjazz/
Ambient chill : http://somafm.com/
Top 40 dance pop rock : http://www.frequence3.fr/
Hip Hop Urban rap : http://www.hot108.com/
Vocal Trance dance pop : http://www.di.fm/
80’s pop rock oldies : http://www.sky.fm/
Alternative pop rock : http://www.idobiradio.com/
Dance Trance Techno House : http://www.pulsradio.com/
Smooth jazz : http://www.smoothjazz.com/

UPDATE: Apparently it is not that simple, according to Minto Gamba. He linked a pretty good explanation in the comments, but you will be able to find it also here.

UPDATE 2 (01-26-08): If it is still not clear to you, watch the explanation of Alexander Burgess, on his blog. As he is DJ in Second Life, he knows what he is talking about.;)