I'll go ahead and list the main bands I tend to listen to (list if from iTunes and is pretty much what I have loaded on the iPod):

ABC, Adam Ant, Aimee Mann, Arested Development, Art Pepper, the Band, Bauhaus, Beatles, Beck, Ben Folds, Berlin, Beta Band, Big Country, Billie Holiday, Billy Idol, Bjork, Black Flag, Blink 182, Blondie, Blue Nile, Blue Oyster Cult, Bob Marley, Bob Mould, Boomtown Rats, Bootsy Collins, Bow Wow Wow, Breeders, Brian Eno, Brian Setzer, Brian Wilson, Brothers Johnson, Bryan Ferry, Buddy Guy, Buffalo Springfield, Burning Spear, Butthole Surfers, Buzzcocks, Byrds, Camper Van Beethoven, Can, Captain Beefheart, Captain Sensible, Cars, Charles Mingus, Cheap Trick, Chet Atkins, Chris Isaak, the Church, Circle Jerks, the Clash, Cocteau Twins, Coldplay, Collective Soul, Colourfield, Combustible Edison, Comsat Angles, Cracker, Cramps, Crash Test Dummies, Cream, Crowded House, Culture Club, Cure, Curtis Mayfield, Damned, Dandy Livingstone, Darkness, Dave Matthews, David Bowie, David Byrne, db's, De La Soul, Dead Boys, Dead Kennedys Dead Milkman, Death Cab for Cutie, Dee-lite, Depeche Mode, Derrick Morgan, Desmond Dekker, Devo, Dexy's Midnight Runners, Dickies, Digable Planets, Dinosaur Jr, Doc Watson, Don Drummond, Donovan, Doors, Doves, Dr. John, Dread Zeppelin, Drivin-n-Cryin, Duran Duran, Dust Brothers, Echo & the Bunnymen, Edwyn Collins, Electrafixion, Elvis Costello, Elvis Presley, English Beat, Erasure, Ethiopians, Eurythmics, Everclear, Faith No More, the Fall, Fear, Fergie, Finn Brothers, Fishbone, Fix, Fleshtones, Flock of Seagulls, Foo Fighters, Frank Black, Frank Zappa, Frente!, Fun Boy Three, Funkadelic, Gary Numan, General Public, Generation X, George Clinton, George Thorogood, Gipsy Kings, the Gladiators, Go Go's, Go West, Godfathers, Gov't Mule, Grace Jones, Grand Funk Railroad, Green Day, Gregory Isaacs, Guadalcanal Diary, Guided by Voices, Gumbo, Guns N' Roses, Gustav Mahler, Haircut 100, Hank Williams Sr, Harry Nilsson, Wawkwind, Heaven 17, Henry Rollins, Hepcat, Hoodoo Gurus, Hot Tuna, Howlin' Wolf, Human Leagure, Husker Du, Ian McCulloch, Icehouse, Icicle Works, Iggy Pop, Indigo Girls, INXS, Israel Vibration, Jackie Mittoo, the Jam, James, James Gang, Jane's Addiction, Japan, Jefferson Airplane, Jesus Jones, Jethro Tull, Jim Croche, Jimi Hendrix, Jimmie Dale Gilmore, Jimmy Cliff, Jimmy Page, Joan Jett, Joe Cocker, Joe Jackson, Joe Strummer, John Coltrane, John Lennon, John Prine, Johnny Cash, Joy Division, Judas Priest, Julan Cope, Kate Bush, Killers, Killing Joke, Kim Wilde, King, King Crimson, Kinks, Kiss, Kraftwerk, Krisin Hersh, Kruder & Dorfmeister, L7, Ladytron, Laurel Aitken, Led Zeppelin, Lee Perry, Lene Lovitch, Leonard Cohen, Les Paul, Lester Bangs, Level 42, Little Feat, Living Colour, Lords of the New Church, Los Lobos, Lou Reed, Love and Rockets, Madness, Magazine, Man or Astroman, Marvin Gaye, Matisyahu, Mathew Sweet, MC5, Meatloaf, Melodians, Men without Hats, Michelle Shocked, Midnight Oil, Mighty Mighty Bosstones, Mike Oldfield, Miles Davis, Minutemen, Missing Persons, Mission of Burma, Modern English, Moody Blues, Morphine, Morrisey, Mudhoney, My Life with the Thrill Kill Kult, 999, Nazareth, Neil Young, Neville Brothers, New Order, New York Dolls, Nick Lowe, Nico, NIN, Nina Hagen, Nirvanna, Nitty Gritty Dirt Band, Oasis, Ohio Players, Oingo Boingo, OMD, Orb, Orbital, Otis Redding, Outkast, Parliament and Pfunk, Patsy Cline, Paul McCartney, Paul Weller, Pavement, Pearl Jam, Pet Shop Boys, Peter Frampton, Peter Gabriel, Peter Murphy, Peter Tosh, Pharoah Sanders, Philip Glass, Phyllis Dillon, Pietasters, Pink Floyd, Pixies, Plimsouls, Police, Pretenders, Primus, Prince, Prince Buster, Prince Jammy, Psychedelic Furs, Public Image Ltd, Pylon, Queen, REM, Radiohead, Ramones, Ravi Shankar, Red Hot Chili Peppers, REplacements, Reverand Horton Heat, Rezillos, Rick Wakeman, Robyn Hitchcock, Roches, Rocket from the Tombs, Rolling Stones, Rollins Band, Romantics, Romeo Void, Roxy Music, Run DMC, Rush, Rusted Root, Ryuichi Sakamoto, Saint Etienne, Samhain, Santana, Sarah McLachlan, Sasha, Scientists, Scritti Politti, Seal, Selector, Sex Pistols, Sham 69, Shonen Knife, Simple Minds, Siouxsie and the Banshees, Sisters of Mercy, Skatalites, Slits, Sly & the Family Stone, Small Faces, Smashing Pumpkins, Smithereens, Smiths, Sneaker Pimps, Social Distortion, Soft Cell, Sonic Yough, Soundgarden, Spandau Ballet, Special, Split Enz, Squeeze, Squirrel Nut Zippers, Steppenwolf, Stereolab, Stiff Little Fingers, Sting, Stone Temple Pilots, Stranglers, Stray Cats, Style Council, SubHumAns, Sugar, Sugarcubes, Suzanne Vega, 311, Talking Heads, Tears for Fears, Television, Tenacious D, Terence Trent D'arby, Thelonious Monk, They Might Be Giants, Thievery Corporation, Thomas Dolby, Thompson Twins, Three Dog Night, Throwing Muses, 'Til Tuesday, Tito Puente, Toasters, Tom Petty, Tom Tom Club, Tom Verlain, Tom Waits, Tool, Toots and the Maytals, Tori Amos, Tracy Chapman, Traffic, Tragically Hip, Traveling Wilburys, Tubes, U2, UB40, Ultravox, Vangelis, Velvet Undergroud, Verve, Violent Femmes, 101'ers, Wall of Voodoo, War, Warren Zevon, Was (Not Was), Ween, Weezer, Wendy Alleyne, Wham, White Stripes, Wilco, Wire, Woody Guthrie, X, X-Ray Specs, XTC, Yardbirds, Yazoo, Yello, Yellow Magic Orchestra, Yes, Yo La Tengo, Ziggy Marley

The list is pretty extensive but each group serves a different purpose.

-- John