I'm glad you started a thread on this topic. I too was frustrated that I didn't recognize all the musicians, or their songs. (For those who didn't see it, the show was all acoustic, and none of the performers were identified. I guess this was a statement that they were putting aside their egos.) I couldn't find a list of them even on the official web site of the program (http://www.tributetoheroes.org/). But I was able to assemble the following list today from various sources on the Internet. I may have missed a few:

Bruce Springsteen (singing a new song, 'My City of Ruins'),

Stevie Wonder ('Love's in Need of Love Today'),

Sting, ('Fragile')

Paul Simon ('Bridge over Troubled Water'),

Eddie Vedder and Mike McCready ('The Long Road')

Willie Nelson (leading 'America the Beautiful' while everyone else, including the actors, joined in - a great finale),

Mariah Carey ('Hero'),

Sheryl Crow,

Billy Joel ('A New York State of Mind'),

Tom Petty ('I Won't Back Down'),

U2,

Celine Dion (why did they pick a Canadian to sing 'God Bless America'?),

the Dixie Chicks,

Wyclef Jean (dressed in stars and stripes, sang Bob Marley's 'Redemption Song')

Faith Hill,

Alicia Keys

Dave Matthews

Jon Bon Jovi

I got the above info from Fox Broadcasting, CBS, USA Today, and E! Online