Here's my all-time top twenty-five:
1) Led Zeppelin
2) Pink Floyd
3) The Cure
4) The Beatles
5) U2
6) REM
7) Steve Earle
8) Aerosmith
9) Prince
10) Bob Dylan
11) The Replacements
12) Big Star
13) The Who
14) Radiohead
15) Crowded House
16) All the grunge era stuff, Nirvana, PJ, Soundgarden, Alice, STP, Mother Love Bone
17) Uncle Tupelo/Son Volt/Wilco
18) Matthew Sweet
19) INXS (rip MH!)
20) The Smiths/Morrissey
21) Third Eye Blind
22) Van Morrison
23) Early Trip-Hop like Portishead, Massive Attack, Tricky
24) The Pixies
25) XTC
Other stuff I like, no particular order: Jeff Buckley (rip!), The Waterboys, Flaming Lips, Queen, Elton John, The Stones, The King, The Boss, Van Halen, Eagles, CCR, Grateful Dead, Skynyrd, Camper Van Beethoven, Toad TWS, Pavement, Primal Scream, Hothouse Flowers, The Alarm, Lyle Lovett, Waylon Jennings, Lucinda Williams, Johnny Cash, Emmylou Harris, Wallflowers, blink-182, sex pistols, the clash, rancid, the ramones, talking heads, new order, erasure, depeche mode, joy division, pet shop boys, mazzy star, grant lee buffalo, bauhaus, love and rockets, sisters of mercy, the cult, elliot smith (rip), pete yorn, tupac shakur (rip), terence trent d'arby, nwa, run-dmc, beastie boys, siouxsie, pretenders, stranglers, bright eyes, spiritualized, white stripes, strokes, hives, killers, matthew good, smashing pumpkins, peter gabriel, NIN, guided by voices, indigo girls, 10,000 maniacs, natalie merchant, sarah mclachlan, the police, oingo boingo, guns n' roses, velvet revolver, jellyfish, travis, oasis, blur, hoodoo gurus, that petrol emotion, ryan adams, the corrs, miles davis, john coltrane, louis armstrong, billie holiday, thelonius monk, charlie parker, JT, carole king, marvin gaye, smokey robinson ...
You guys get the picture yet? I could do this all day, but suffice to say: my ipod is pretty diverse...
Tunes that came out fairly recently I dig on:
M.I.A. - "Paper Planes"
This song is friggin bad@$$:
http://www.youtube.com/watch?v=fCFN1XwDOqE
Foo Fighters - "The Pretender"
Eagles - "How Long"
Nickelback - "Figure You Out"
Fergie - "Big Girls Don't Cry" (video came out when I was dopesick, made me bawl like 20 different times - and I ain't even a girl!)