Bookmark a url

How can I bookmark online radio stations so I don't have to keep opening my browser to grab the url? I realise I could just create a playlist, but the url of the station is itself a playlist (.m3u or .pls) , so the broadcasters can change the urls to which the playlist points. If I bookmark these they may have changed next time I want to listen to the station.
I know there is a bookmark option under the Engage button, but I can't work out how to make it bookmark urls rather than local files.