"We're gonna try something dangerous and special," Bono said halfway through U2's closing set on the second night of the Rock and Roll Hall of Fame 25th anniversary concert. The singer had already brought out Bruce Springsteen and Patti Smith for a version of 'Because The Night,' a song Bono said "we wish we had written."

It required two takes, but ultimately proved magical, with Springsteen soloing on guitar as Smith and Bono exhorted him on. The Black Eyed Peas then joined the band for 'Where Is The Love,' which Bono called "a forever song." The imagination ran a little wild at the prospect of this collaboration. But with Fergie standing above the drum stand dancing and Bono strumming a guitar, the fantasies of the Madison Square Garden fans couldn't dream up what U2 delivered next.

As the intro morphed into 'Gimme Shelter,' a spry Mick Jagger sauntered onto the stage, sending the Garden into a collective frenzy. Just the sight of the unannounced Jagger was enough to raise the arena to its feet, but seeing Jagger and Bono trading notes and Fergie going to toe to toe with Jagger, singing the song's famed background vocals, was as musically rich as the names involved.

After the Peas triumphantly exited the stage to a huge ovation and hugs from all involved, Jagger quipped, "What should we do now?" The Rolling Stones frontman and Bono then delivered a spot-on duet of 'Stuck In A Moment You Can't Get Out Of,' expertly rehearsed just as Springsteen and Bono's earlier duet for 'I Still Haven't Found What I'm Looking For.' Just as Springsteen had the night before, U2 donated most of their set to other musicians, mixing in originals like 'Mysterious Ways,' the opening 'Vertigo,' and the grand finale, 'Beautiful Day,' with collaborations.

The formula worked equally well for Metallica earlier in the night. "We're not a jammy band," James Hetfield said. "We're a pretty tight unit." But Hetfield ended up surprising himself. "Wow, maybe we can jam," he concluded later in the night. Clearly any band that can double as the backing band for Lou Reed, Ozzy Osbourne, and the Kinks' Ray Davies, as Metallica did last night, has proved its versatility. Among the high points were Reed leading the metal monsters in 'Sweet Jane,' Osbourne's spectacular 'Iron Man' and 'Paranoid,' and Davies, deservedly lapping up the spotlight, jumping around as the ensemble rocked to 'You Really Got Me' and 'All Day And All Of The Night.' Even Hetfield questioned the match, saying it didn't make sense to them at first, but they learned their lesson. Introducing Davies, they said, "We got schooled by this guy in riff rock."

Many of the headliners of the night found themselves in similar positions and relished it. For real music lovers, the opportunity to see some of the giants back in the spotlight will be the most indelible images of the two days. For instance, Jeff Beck, who brought out Sting for Curtis Mayfield's classic 'People Get Ready,' was feted as a guitar hero who capably filled the shoes of the missing Eric Clapton, who canceled his appearance due to illness. If Clapton and his vast catalog was missed, Beck was up to the challenge, showing off his masterful skill and incredible ease as he backed ZZ Top's Billy Gibbons on a cover of Jimi Hendrix's 'Foxy Lady' and brought the Garden to its feet with an instrumental take of the Beatles' 'A Day In The Life.'

Rounding out the main acts was Aretha Franklin, joined at points by Annie Lennox and Lenny Kravitz for a walk through her considerable musical legacy. But everybody on the stage could lay claim to the same, and brought that legacy to the stage as best they know how: by rocking.