Even for casual fans of hip-hop, Riverfest bagging the "Freaks of the Industry" for this year's festival is epic. In the early-'90s explosion of L.A.-centric East Coast rap, Digital Underground provided an irreverent wit and G-Funk mutating hip-hop to offset the politically charged, status quo-shocking tone of the day. The group's conceptual debut album "Sex Packets" is essential listening, manic and lewd with classics like "Doowutchyalike" and, of course, the Edward G. Humphrey — better known as Humpty Hump — moment in the sun, "The Humpty Dance." Little Rock, this could be your only "chance to do the hump." Don't mess it up.

Sure, we can debate whether or not Nelly is still relevant in 2011. His last handful of singles slipped out of earshot as soon as they appeared, maybe because the St. Louis rapper has focused on his omnipresent clothing line, Apple Bottom Jeans, and his other business ventures instead of the music. We could debate it. Or we could talk about any how, 11 years later, you can resuscitate a dying party in a flash by throwing on, well, just about any of Nelly's first singles. "Country Grammar (Hot Shit)," "E.I.," "Hot in Herre," "Pimp Juice": Believe you me, they all work. He's made a career out of reconstituting schoolyard rhymes, rural twang and club-ready production into a tongue-twisting, juking style of rap that managed to capture the mood of the strange, genre-twisting thing known as Southern club rap with ass-shaking ease.

Marky Mark begat Justin Timberlake, who then begat Robin Thicke, who then begat Mike Posner. A Bonnaroo and Warped Tour Veteran, Mike Posner is the latest contestant in the white-boy pop-rap/synth-soul fame game, crafting college party anthems made for the frat house and straight out of the frat house. In fact, the bulk of his debut album, "31 Minutes to Takeoff," was culled from home recordings he made while attending Duke. Sure, the guy is going to take his share of licks, but he's just now 23 and has already collaborated with rap giants like Lil Wayne and Bun B, as well as buzzy emcees Wale and Big Sean.

It's not a summer festival until the requisite Dad rockers whisk the crowds back to the golden days of medium-wave radio, tight jeans and feathered hair. Throughout the '70s and '80s, REO Speedwagon's M.O.R. take on arena rock shot the Illinois working-band-done-good to the near-apex of tour circuit fame, not to mention the charts. The 1980 album that contains "Keep On Loving You" and "Take It on the Run," "Hi-Infidelity," has sold 10 million copies. Sure, the cheese has aged in the last 30 years, but when a band can craft a hook that's still sticky, sweet and unshakable generations later, it's hard to argue with its successes.

One of the bigger bands to be christened by the Angst Rock Band Name Generator, Blue October has been active for 16 years, gigging around its native Houston and enjoying regional success for the bulk of its career. However, in 2006, the band's breakthrough piece of self-loathing, "Hate Me," put the post-grunge outfit on the Modern Rock Charts and on heavy rotation on VH1. (Sample lyric: "I have to block out thoughts of you so I don't lose my head/They crawl in like a cockroach leaving babies in my bed." Eek.)

Frontman and principal songwriter Justin Furstenfeld isn't faking the fret, though: The mohawked rocker with the smeared raccoon makeup has been in and out of his share of mental hospitals. Also in and out of book tours: He joined "Twilight" scribe Stephenie Meyer on a joint book/concert tour in 2008. Earlier this month, Blue October released "Ugly Side," a live acoustic album. This August, the band plans to release "Any Man in America," its ninth album to get, well, down to.

It's only appropriate that Papa Roach just won't die. One of the big names from the late-'90s/early-'00s rap-rock and nu-metal boom, the band found itself in the spotlight with "Infest," the group's triple Platinum album, and its standout single, "Last Resort." (When the aliens come and ask about nu-metal, that's the one you're going to want to play.) Over the following years, Papa Roach squeezed the angry guitar wall and caterwauling vocals dry. Since, the band has been busy mining sleaze-rock and L.A. goth-glam in singles like "Hollywood Whore" and "I Almost Told You That I Loved You." The mood may have changed, but there's still no shortage of rap-metal wannabes still aping that "Last Resort" sound. Not just inspiring young guns in the rock realm, we're pretty certain that Papa Roach's iconography — blade-edge typography and blown out color scheme — is single-handedly responsible for every single Tapout shirt ever.

This show marks the first time that the irreverent Canadian pop act of Barenaked Ladies has played Arkansas: a shocker, considering that the band has never been shy about taking its loose banter-and-comedy-spiced show on the road. The band hit it big in 1998 with "One Week," the '90s-defining bit of half-sung, half-rapped irreverence that unleashed "Chickety China, the Chinese Chicken" on an unsuspecting public. Barenaked Ladies stayed tacked onto radio playlists with "It's All Been Done" and "Pinch Me," two more pieces of trademark harmonic pop. Festival-goers too young to have seen the band's heyday will probably recognize the band as "those guys who did the theme song for 'How I Met Your Mother.' " Riverfesters even younger than that may recognize them as "the guys who made 'Snacktime!'," the award-winning (and, creepily enough, relistenable) 2008 children's album. Sir Paul McCartney may recognize the band as "the guys that I once said could outsing John Lennon and I."

Few L.A. bands have ever come close to reaching the heights of drug-, groupie- and hair spray-fuelled excesses of Poison. The late '80s saw the androgynous cock-rockers become one of the biggest bands in the world, going multi-platinum time after time again thanks to their cartoonish sleaze, mom-baiting antics and ridiculously catchy string of singles like "Nothin' but a Good Time," "Unskinny Bop" and the crowned king of the '80s power ballad "Every Rose Has Its Thorn." While the "dumber we do it, the sweeter it sounds" plan was a huge success in the studio, Poison was notorious for the live show: confetti, pyro, costumes and flashers galore. Say what you will about Bret Michaels, but you can't argue that the guy is a dedicated entertainer. Since reinventing himself as a reality TV star on "Celebrity Apprentice" and his VH1 dating show "Rock of Love," Michaels spent chunks of 2010 in the hospital, finding himself in critical condition after suffering a debilitating brain hemorrhage. Now he's rehabilitating on the road and celebrating Poison's 25th anniversary.

For every beard hair that wound out of Jerry Garcia's round face, there's a band trying to re-capture a bit of Grateful success. With the exception of Phish and, if you insist, Dave Matthews Band, no band has brought Southern-fried, purple-hazed noodle-rock to the masses with as much success as Widespread Panic. Since 1983, the band has been the focal point for legions of fans who, as is the jam tradition, chronicle every note of every concert. Seeing as how these guys are consummate road warriors, that's a lot of tape. And tonight, expect the reels to roll long: Riverfest organizers have given Panic three-plus hours to bring the long-winding choogle to the river.