line = 3;
banner = new Array(
'<a href=/shop><img src=/img/bn/bn_waltz.jpg></a>',
'<a href=http://mixi.jp/view_community.pl?id=386610><img src=/img/bn/bn_mixi.jpg></a>',
'<a href=http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewArtist?id=267858607&forceArtistPage=1><img src=/img/bn/bn_itms.jpg></a>'
);
rnd = Math.floor(Math.random()*line);
document.write(banner[rnd]);