figured them out:

rewrite ^/bg_sound_([^_]*)\.xspf$ /includes/bg_audio_player/bg_sound.php?tributeid=$1 break;
rewrite ^/adamcarter$ /tributedetails.php?name=elvis_adam_carter&page=1 break;

I have one problem now, that is that they are not processed by php as the rewrites are in the "location /" and not "location ~.*php$", is their any way to fix this other than putting the fastcgi lines in the "location /" section?