Here are a somewhat ordered list of some of my favorite bands (and great albums):
Hiphop
Black Star, De la Soul, A Tribe Called Quest, Beasie Boys, Atmosphere, Lyrics Born, Blackalicious,
Downtempo
DJ Food, DJ Shadow, 9 Lazy 9, DJ Krush, Kid Loco, DJ Vadim,
NuJazz
Jaga Jazzist, St. Germaine, Up, Bustle & Out,
Indy Rock
Wolf Parade, Arcade Fire, Yo la Tengo, Broken Social Scene, Death Cab for Cutie, Sigur Ros, Mum, Mogwai, Do Make Say Think, God Speed You Black Emporer, A Silver Mt. Zion, Archeticture in Helsinki,
Rock
Radiohead, Built to Spill, White Stripes, Royal Trux,
Electronica
Air, Boards of Canada, Blue States, Amon Tobin, Bonobo, Tosca,
Oldies
Pink Floyd, Led Zeppelin, The Beatles, The Grateful Dead, BoB Dylan, Neil Young, Cream, Alan Parsons Project, The Doors,
Country
Johnny Cash, Townes Van Zandt
Jazz
Miles Davis, Billie Holliday, Ella Fitzgerald, John Coletrain, Nina Simone, Oscar Peterson, Pete Fontaine,
Blues
Muddy Waters,