Used to change the url for your room. The URL of your room will be available to any user that requests info on your room. Rooms do not need attached URLs.
Example:
/msg chanserv set #ConferenceRoom url http://www.webmaster.com
Setting an URL can be very useful if it contains rules that relate to the room or frequently asked questions. You can set the URL to anything, but people will generally expect the URL to relate to the room in some way. More social rooms sometimes have web sites that give information about the people who regularly chat there.