Some 911 tribute songs that I found - Listen (Although I find it hard listening to Bush speak))

Pearl Jam and Neil Young doing Neil Young's 'Free World '
http://www.pro-american.com/Music/World%20Trade%20Center%20(WTC)%20-Rockin%20In%20The%20Free%20World%20-%20Perl%20Jam.Mp3

Jewel does 'Hands'
http://img.buzznet.com/assets/audiox/1/4/2/2/3/14223.mp3