Ooh, I like this. My husband (British) and I (American) are big-time music nerds, and spend way way too much money on listening to/buying music! These are just some of our favorites, but we both have almost maxed out 40 gig iPods, so it's just a small selection:
British
Elbow, Archie Bronson Outfit, Clinic, Idlewild, King Creosote, La's, Smiths, Morrissey, The Cure, Sons & Daughters, David Bowie, Donovan, Radiohead, Echo & the Bunnymen, Elvis Costello, the Cribs, the Fall, Muse, Futureheads, Jesus and Mary Chain, Joy Division, Maximo Park, Led Zep,
American
The Brian Jonestown Massacre, The Black Keys, Modest Mouse, The National, Warlocks, Black Angels, Kings of Leon, Midlake, My Morning Jacket, NIN, Elliot Smith, Devendra Banhart, Iron and Wine, Pixies, Fugazi, The Shins, Two Gallants, Band of Horses, Blonde Redhead, Willy Mason, BRMC, Devo, Eels, Queens of the Stoneage, Grandaddy, Ramones, REM, Smashing Pumpkins, Spindrift, They Might Be Giants, Tool, Tom Waits...
gosh, there's so much great music in this world, and so little time to listen to it all!