A bookmarklet to move you from one music playback service to another. Can take you to MOG or to Rdio from pages on MOG, Rdio, Last.FM, Spotify, and some MySpace pages. Set `using: 'mog'` or `using: 'rdio'` as appropriate. Work in progress.

playmusic-full.js

PlayMusic = {
  using: 'mog',
  esc: function(s) {
    return s.replace(' ', '-');
  },
  sources: {
    'rdio': {
      match: /rdio.com/,
      handler: function(url) {
        var artist='', album='', track='';
        var parts = url.split('/');
        for(var i=0; i < parts.length; i++) {
          p=parts[i];
          switch(p) {
          case 'artist':
            i = i+1; 
            artist = parts[i];
            break;
          case 'album':
            i = i+1;
            album = parts[i];
            break;
          case 'track':
            i = i+1;
            track = parts[i];
            break;
          default:
            break;
          }
        }
        return { artist: artist, album: album, track: track };
      }
    },
    'spotify': {
      match: /spotify\.com/,
      handler: function() {
        var track='', artist='', album='', 
            links = document.getElementsByTagName('a');
        for(var i=0;l=links[i];i++) {
          if(l.href.match(/^spotify:track:/)) {
            track = l.innerText;
          }
          else if(l.href.match(/open.spotify.com\/artist/)) {
            artist = l.title;
          }
          else if(l.href.match(/open.spotify.com\/album/)) {
            album = l.title;
          }
        }
        return { artist: artist, album: album, track: track };
      }
    },
    'mog': {
      match: /mog\.com/,
      handler: function(url) {
        
        url = url.replace(/\-/g, ' ');
        
        var parts = url.match(/(artists|albums|tracks)\/mn[0-9]+\/([a-z0-9\-]+)(\/([a-z0-9\-]+))?(\/([a-z0-9\-]+))?/i);
        var rtn = {};
        if(parts[2]) {
          rtn.artist = parts[2];
        }
        if(parts[4]) {
          rtn.album = parts[4];
        }
        if(parts[6]) {
          rtn.track = parts[6];
        }
        return rtn;
      }
    },
    'lastfm': {
      match: /(last\.fm|lastfm\.[a-z]{2,3})/,
      handler: function(url) {
        
        url = url.replace(/(\+|%20|_)/g, ' ');
        
        var parts = url.match(/(music(\/\+noredirect)?)\/([a-z0-9\-]+)(\/([a-z0-9\-]+))?(\/([a-z0-9\-]+))?/i);
        
        // Handle Last.FM track view outside of an album context.
        if('_' === parts[5]) {
          parts[5] = undefined;
        }
        var rtn = {};
        if(parts[3]) {
          rtn.artist = parts[3];
        }
        if(parts[5]) {
          rtn.album = parts[5];
        }
        if(parts[7]) {
          rtn.track = parts[7];
        }
        return rtn;
      }
    },
    'hypem': {
      match: /hypem.com/,
      handler: function(url) {
        url = url.replace(/\+/g, ' ');
        console.log(url);
        if(match = url.match(/artist\/(a-z )/i)) {
          return { artist: match[1], album: undefined, track: undefined };
        }
        else if(match = url.match(/track\/[0-9]+\/(.+)/i)) {
          split = match[1].split(' - ', 2);
          console.log(split);
          return { artist: split[0], track: split[1], album: undefined };          
        }
        else {
          return undefined;
        }
      }
    },
    'myspace': {
      match: /myspace\.com/,
      handler: function() {
        artist = document.getElementsByClassName('userLink')[0].innerText;
        return { artist: artist };
      }
    }
  },
  dest: {
    'mog': {
      redirect: function(t) {
        var url = undefined;
        if(t.artist) {
          url = 'http://mog.com/music/'+t.artist.replace(/ /g,'-');

          if(t.album) {
            url+='/'+t.album.replace(/ /g,'-');

            if(t.track) {
              url+='/'+t.track.replace(/ /g,'-');
            }
          }
        }
        return url;
      }
    },
    'rdio': {
      redirect: function(t) {
        var url = undefined;
        if(t.artist) {
          url = 'http://rdio.com/artist/'+t.artist;

          if(t.album) {
            url += '/album/'+t.album.replace(/ /g,'_');

            if(t.track) {
              url += '/track/'+t.track.replace(/ /g,'_');
            }
          }
        }
        return url;
      }
    } 
  },
  redirect:function() {
    for(service in PlayMusic.sources) {
      if(window.location.href.match(PlayMusic.sources[service].match)) {

        if(PlayMusic.using === service) {
          console.log("Can't redirect away; this site is configured as your prefered playback service!");
          return;
        }
        music_info = PlayMusic.sources[service].handler(window.location.href);
        
        if(undefined === music_info) {
          alert("Sorry, couldn't figure out a destination URL for this page.");
          return;
        }
        
        otherplace = PlayMusic.dest[PlayMusic.using].redirect(music_info);
        
        if(undefined === otherplace) {
          alert("Sorry, couldn't figure out a destination URL for this page.");
          return;
        }
        window.location.href = otherplace;
        return;    
      }
    }
    alert("Sorry, couldn't translate this page into a music URL");
    return;
  }
};
PlayMusic.redirect();

playmusic.js

javascript:PlayMusic%20=%20{using:%20%27mog%27,esc:%20function(s)%20{return%20s.replace(%27%20%27,%20%27-%27);},sources:%20{%27rdio%27:%20{match:%20/rdio.com/,handler:%20function(url)%20{var%20artist=%27%27,%20album=%27%27,%20track=%27%27;var%20parts%20=%20url.split(%27/%27);for(var%20i=0;%20i%20<%20parts.length;%20i++)%20{p=parts[i];switch(p)%20{case%20%27artist%27:i%20=%20i+1;artist%20=%20parts[i];break;case%20%27album%27:i%20=%20i+1;album%20=%20parts[i];break;case%20%27track%27:i%20=%20i+1;track%20=%20parts[i];break;default:break;}}return%20{%20artist:%20artist,%20album:%20album,%20track:%20track%20};}},%27spotify%27:%20{match:%20/spotify\.com/,handler:%20function()%20{var%20track=%27%27,%20artist=%27%27,%20album=%27%27,links%20=%20document.getElementsByTagName(%27a%27);for(var%20i=0;l=links[i];i++)%20{if(l.href.match(/^spotify:track:/))%20{track%20=%20l.innerText;}else%20if(l.href.match(/open.spotify.com\/artist/))%20{artist%20=%20l.title;}else%20if(l.href.match(/open.spotify.com\/album/))%20{album%20=%20l.title;}}return%20{%20artist:%20artist,%20album:%20album,%20track:%20track%20};}},%27mog%27:%20{match:%20/mog\.com/,handler:%20function(url)%20{url%20=%20url.replace(/\-/g,%20%27%20%27);var%20parts%20=%20url.match(/(artists|albums|tracks)\/mn[0-9]+\/([a-z0-9\-]+)(\/([a-z0-9\-]+))?(\/([a-z0-9\-]+))?/i);var%20rtn%20=%20{};if(parts[2])%20{rtn.artist%20=%20parts[2];}if(parts[4])%20{rtn.album%20=%20parts[4];}if(parts[6])%20{rtn.track%20=%20parts[6];}return%20rtn;}},%27lastfm%27:%20{match:%20/(last\.fm|lastfm\.[a-z]{2,3})/,handler:%20function(url)%20{url%20=%20url.replace(/(\+|%20|_)/g,%20%27%20%27);var%20parts%20=%20url.match(/(music(\/\+noredirect)?)\/([a-z0-9\-]+)(\/([a-z0-9\-]+))?(\/([a-z0-9\-]+))?/i);if(%27_%27%20===%20parts[5])%20{parts[5]%20=%20undefined;}var%20rtn%20=%20{};if(parts[3])%20{rtn.artist%20=%20parts[3];}if(parts[5])%20{rtn.album%20=%20parts[5];}if(parts[7])%20{rtn.track%20=%20parts[7];}return%20rtn;}},%27hypem%27:%20{match:%20/hypem.com/,handler:%20function(url)%20{url%20=%20url.replace(/\+/g,%20%27%20%27);console.log(url);if(match%20=%20url.match(/artist\/(a-z%20)/i))%20{return%20{%20artist:%20match[1],%20album:%20undefined,%20track:%20undefined%20};}else%20if(match%20=%20url.match(/track\/[0-9]+\/(.+)/i))%20{split%20=%20match[1].split(%27%20-%20%27,%202);console.log(split);return%20{%20artist:%20split[0],%20track:%20split[1],%20album:%20undefined%20};}else%20{return%20undefined;}}},%27myspace%27:%20{match:%20/myspace\.com/,handler:%20function()%20{artist%20=%20document.getElementsByClassName(%27userLink%27)[0].innerText;return%20{%20artist:%20artist%20};}}},dest:%20{%27mog%27:%20{redirect:%20function(t)%20{var%20url%20=%20undefined;if(t.artist)%20{url%20=%20%27http://mog.com/music/%27+t.artist.replace(/%20/g,%27-%27);if(t.album)%20{url+=%27/%27+t.album.replace(/%20/g,%27-%27);if(t.track)%20{url+=%27/%27+t.track.replace(/%20/g,%27-%27);}}}return%20url;}},%27rdio%27:%20{redirect:%20function(t)%20{var%20url%20=%20undefined;if(t.artist)%20{url%20=%20%27http://rdio.com/artist/%27+t.artist;if(t.album)%20{url%20+=%20%27/album/%27+t.album.replace(/%20/g,%27_%27);if(t.track)%20{url%20+=%20%27/track/%27+t.track.replace(/%20/g,%27_%27);}}}return%20url;}}},redirect:function()%20{for(service%20in%20PlayMusic.sources)%20{if(window.location.href.match(PlayMusic.sources[service].match))%20{if(PlayMusic.using%20===%20service)%20{console.log(%22Can%27t%20redirect%20away;%20this%20site%20is%20configured%20as%20your%20prefered%20playback%20service!%22);return;}music_info%20=%20PlayMusic.sources[service].handler(window.location.href);if(undefined%20===%20music_info)%20{alert(%22Sorry,%20couldn%27t%20figure%20out%20a%20destination%20URL%20for%20this%20page.%22);return;}otherplace%20=%20PlayMusic.dest[PlayMusic.using].redirect(music_info);if(undefined%20===%20otherplace)%20{alert(%22Sorry,%20couldn%27t%20figure%20out%20a%20destination%20URL%20for%20this%20page.%22);return;}window.location.href%20=%20otherplace;return;}}alert(%22Sorry,%20couldn%27t%20translate%20this%20page%20into%20a%20music%20URL%22);return;}};PlayMusic.redirect();