America: Ventura Highway
CCR: Up Around The Bend
Supertramp: The Logical Song
Baba O’Reilly was the first one to come to my mind, though Won’t Get Fooled Again popped up soon after.
Either way: Who’s on First, and awesome early use of synth along with perfect power chord rock and Daltrey’s frontman scream.
Everclear: “Santa Monica”
Many of their songs have the same rhythm, which is epitomized in their first hit.
Actually, when I saw the thread title, I figured I’d say: Supertramp - Dreamer
But The Logical Song is a purty good choice too.
This is surprisingly tough… the most representative song isn’t necessarily [indeed, probably shouldn’t be] the best, or the best known. Boiling it down to one is going to short-change those artists who evolved from one style to another (and another, and another) over the years. But here’s mine:
Roxy Music: “The Thrill of It All”
Earth, Wind & Fire: “September”
Elvis Costello: “What’s So Funny (About Peace, Love and Understanding?)”
Joy Division: “These Days”
King Crimson [1980-]: “Thela Hun Ginjeet”
XTC: “Senses Working Overtime”
Crowded House: “Don’t Dream It’s Over”
Talking Heads: “Crosseyed and Painless”
The Golden Palominos: “Something Becomes Nothing”
Depeche Mode: “Enjoy the Silence”
Robyn Hitchcock: “My Wife and My Dead Wife”
The The: “Slow Emotion Replay”
REM: “Try Not to Breathe”
Pixies: “Something Against You”
Pavement: “Range Life”
Pulp: “Common People”
Massive Attack: “Unfinished Sympathy”
Muse: “New Born” [live] 
Elbow: “An Audience With the Pope”
Boston: More than a Feeling
Do One hit Wonders count?
The Doors: Light My Fire.
Bob Rivers : The Twelve Pains of Christmas
The Offspring: She’s Got Issues
Well, contrary to popular belief, the Smithereens’ songs are NOT all the same with just slightly different lyrics…but there are rather a lot of similarities throughtout their albums. That said, I’d state “Only a Memory” is rather a good signature song to represent them.
And in the same vein, lets go with “Someday” for Nickelback.
Neil Diamond: pick one, they’re all nearly identical.
Beck - Odelay - Full of electronic wizardry, tons of samples, and near-nonesense, but catchy lyrics
White Stripes - Hardest button to button - great hook and riff, bluesy, but also kinda heavy
**Rolling Stones **- Satisfaction - Bluesy rocker with an awesome guitar riff and some seedy undertones in the lyrics
Nirvana - Smells Like Teen Spirit - An obvious, but appropriate choice. Angsty, hard-rocking song
Green Day - When I Come Around - Fun, loud, anthemic song. Maybe not as political as they’ve become, but I still think relevent.
I’ll throw my opinion on “single most representative song” for ten giants of classic rock, most already mentioned:
Bob Dylan: Like A Rolling Stone. I wish I could also include “Ballad Of A Thin Man”.
The Rolling Stones: Sympathy for the Devil. Runners up: Gimme Shelter, Shine A Light
The Who: Won’t Get Fooled Again. Very close on Baba O’Riley though.
Pink Floyd: Time (from DSotM). Runners up: Dogs (Animals), Hey You (The Wall)
Led Zeppelin: Whole Lotta Love. Surprised nobody’s mentioned it yet. Though there are many to choose from, for me, this is THE Led Zep song.
The Beatles: So many different sounds from this band from different albums. I’ll go with “A Day In The Life”, if “The Sun King Medley” isn’t cheating.
Jimi Hendrix: House Burning Down. Runners up: Voodoo Chile (Slight Return), Are You Experienced?, Foxy Lady
U2: Who’s Gonna Ride Your Wild Horses. Lots of favorites but that song really captures their sound to me.
Bruce Springsteen: Rosalita (Come Out Tonight). Also surprised this hasn’t been mentioned.
Janis Joplin: Kozmic Blues. Close runner-up: her live recording of Ball and Chain.
Interesting that there are so many different choices for Led Zeppelin. For what it’s worth, there’s a specific quote from Jimmy Page (that may or may not come from Hammer of the Gods; it’s been a long time since I read it) where he references this very topic, and talks about how The Who’s signature was “Won’t Get Fooled Again”. His choice for Zeppelin? “Stairway to Heaven”. Plant’s choice? “Kashmir”. I agree with Pagey, although my personal favorite Zep song is actually “The Ocean”.
I’ll agree with “Won’t Get Fooled Again” for The Who. Let’s see, what else . . .[ul][]Black Sabbath: “N.I.B.” from the first album. Probably not a typical choice (which would be “Paranoid”), but to me, that encapsulates that band’s sound.[]The Doors: “When the Music’s Over” - preferably the live version from the original Absolutely Live album.[]AC/DC: This is tough, because I see them as two different eras. For Bon Scott’s era, I would say “Let There Be Rock”, for Brian Johnson, “You Shook Me All Night Long”.[]Def Leppard: “Rock of Ages”[]Dire Straits: “Tunnel of Love”[]The Eagles: Another band that exists in two different eras, in this case pre- and post- Joe Walsh. For the former, I would say “Lyin’ Eyes”, for the latter, “Life in the Fast Lane”[]The Offspring: “Come Out and Play”[]Tom Petty: “Refugee”[]The Ramones: “I Wanna Be Sedated”[]The Rolling Stones: “Satisfaction”Stevie Ray Vaughan: “Pride and Joy”[/ul]
The Kinks, “Sunny Afternoon”
The Allman Brothers Band, “Midnight Rider” (I was gonna go with Statesboro Blues, but that’s a cover, so…)
White Stripes, “I’m In Love With a Girl”
Miami Sound Machine - Absolutely any song they recorded.
If you had to pick a Nirvana song I’d certainly pick that. But ironically, if all Nirvana songs were more like SLTS, they would be remembered for being grunge, but also for being an emocore pioneer (since in that song the melodic punk, loud/soft dynamic, incomprehensible teenage lyrics, and whiny voice come together moreso than in their other songs.)
The Ramones - Sheena is a Punk Rocker