Jeff Tweedy and Mavis Staples embrace after the Wilco frontman appeared for a duet with the legendary soul singer on Friday afternoon. For more photos, see our full coverage »

MUSIC Every fest has its moments, and Lollapalooza 2010 was no exception. This year, we picked the most memorable—including best multi-generational act, greatest dance party of the year, and our favorite show for funky fan watching.

BEST BEAT LIKE A HAMMER: Emily Haines—the sartorial front woman of the Canadian rock group Metric—milking the lyrics of the song “Help, I’m Alive” to the point that the entire crowd was crying out about their hearts “beating like a hammer.” Even those who didn’t know the song were swayed by the end, proof that Metric’s infectious combo of dance pop and dark, grooving rock made for one of the weekend’s best performances.

BEST GROUP HUGS AND SING-ALONGS: Curiously relegated to a side stage, psychedelic-folk troubadours Edward Sharpe & the Magnetic Zeros had zealous fans standing on garbage cans, climbing trees, and sitting on one another’s shoulders just so they wouldn’t miss any of front man Alex Ebert’s antics. Playing mostly hits from the band’s 2009 album “Up From Below,” Ebert mesmerized his audience to the point that when he asked them to take a seat for a quieter solo, hundreds actually plopped down in the muddy grass. But our favorite moments were his duets with the band’s female singer Jade Castrinos—together, they reminded us of a modern day Johnny Cash and June Carter

BEST TIME FOR VINDICATION: In 2007, an unknown (but still scantily clad) Lady Gaga played a poorly attended show at the BMI side stage. We wrote about it, calling her a “horny man’s Amy Winehouse,” but giving her some measured praise for her voice, her unfettered enthusiasm, and her homemade sparkly bra. In an impassioned soliloquy on Friday, Gaga (wearing that same sparkly bra, natch) told the masses of her trajectory from forgotten side stage to main stage and reminded us repeatedly in her own after-school-special-meets-burlesque-way that, yes, even freaks can become superstars.

BEST FAN WATCHING: Androgyny, guitar fury, flames and explosions from X Japan, a Japanese hair metal supergroup that was making its American debut. They were not the tightest band we saw in the technical sense, but their flag-toting Japanese fans definitely made their Sunday afternoon set the best occasion for people watching.

BEST DANCE PARTY OF THE YEAR: On Friday night, the eclectic 2manydjs set went cross-platform. Brothers David and Stephen Dewaele, also of Soulwax, led the crowd against the backdrop of a slideshow that drew on retro, pop-art influences (think Saturday Night Fever album art) and pulsed along with the duo’s electronic hooks. By Sunday, back-to-back local spinners Flosstradamus and Felix Da Housecat kept the packed crowd bouncing, turning the tiny field into an open-aired club.

BEST MOMENT FOR MODERN SOUL: Legendary Chicago soul singer Mavis Staples recently collaborated with Jeff Tweedy, and we were curious if the Wilco frontman would show for her set. He did—and his mild-mannered presence sent Staples beaming into “You Are Not Alone,” the title track off the forthcoming album (which he produced). The tender song brought Staples to tears the first time she heard it, and at Lolla, she put all of that emotion into the lyrics, showcasing the range and power of her vocals.

BEST MULTI-GENERATIONAL ACT: On Friday, the aging rockers Devo reminded a pre-Gaga crowd where pop-as-performance-art got its start. Their kooky, costumed set sent a cross-generational crowd into a sing-a-long dance party. As Bob Mothersbaugh said, “It’s 2010 and we’re here to f’ing ‘Whip It,’ again.” Dome hats and all.

BEST RETURN TO WITNESS: In 2007, energy-packed Brooklyn duo Matt and Kim played at 11:45 a.m. on a smaller stage to a tiny group. Three years and a few TV shows and commercials later (their songs were featured on Entourage, Community, and Gossip Girl) the synth-and-drum pair brought back their bouncy pop-punk to Lolla, playing at 5 p.m. to a huge crowd on a big stage. Nothing captured the party atmosphere like Kim Schifino’s crowd-surfing booty dance. With clear instructions to the crowd to keep her feet level and not too far apart, Schifino crawled out into the mob, stood up slowly, and got low dancing to Major Lazer’s “Pon de Floor.” And this is how crowd-surfing should be done.

BEST LAID-BACK GROOVE: Reggae founding father Jimmy Cliff offered a lesson in how to get old on Friday night with slick dance moves and tireless vocals. Fans were waiting to hear Cliff’s classics from “The Harder They Come” soundtrack, but covers of “Wild World” and “I Can See Clearly Now” turned into group sing-a-longs, encouraged by Cliff’s wide grin. As a friend said, “I don’t think Gaga could make me this happy.”

BEST REMINDER THAT ROCK STILL RULES: Love Gaga or detest her, there was a mass exodus from her set to The Strokes. Yes, over-the-top pop may be the thing of the moment, but great rock still reigns.

Photograph: Esther Kang