Here are a list of known Songbird easter eggs :

• Kanye West: http://nzf.turmel.info/opengrok/xref/nightingale-hacking/app/content/bindings/sbSearch.xml#254
• Prince: http://nzf.turmel.info/opengrok/xref/nightingale-hacking/extensions/AlbumArt/chrome/content/albumArtPane.js#307
• DRM: http://nzf.turmel.info/opengrok/xref/nightingale-hacking/components/protocol/sbAboutDRM.js#78
  • One of the two blacklisted usernames is redfive, haven't found the other one yet.
• Contributors photos in mashTape: http://nzf.turmel.info/opengrok/xref/nightingale-hacking/extensions/mashTape/components/src/Flickr.js#57
• Concerts: http://nzf.turmel.info/opengrok/xref/nightingale-hacking/extensions/concerts/chrome/content/browse.js#296