Pandora.com

Pandora is a spin-off of the Music Genome Project, an ambitious undertaking to break down songs like DNA strands, analyzing them on qualities as specific as "rhythmic syncopation" and "key tonality." The result is your own personal radio station — one that anticipates what you'll like based on as little as a single artist or favorite song. -Doug Levy

3hive.com

3Hive is one of the few MP3 blogs considerate enough to archive its past posts. The site now hosts hundreds of free tracks — from fractured hip-hop to slowcore — all conveniently searchable by genre, artist, and label, creating such a dense network of its curators' collective music knowledge that the site hums with energy. -Todd Goldstein

Spoiltvictorianchild.co.uk

It's not often that an MP3 blog's written content actually competes with its audio content, but faced with Spoilt Victorian Child's succinct, poignant observations on music and life — which are nestled between sterling cuts (e.g. melancholic old soul sides, obscure electronic twiddling, forgotten Brit-poppery) — it becomes clear that the site's readers are the ones who are spoiled. -Todd Goldstein

Emusic.com

A hard-disk record collector's wet dream, eMusic features over 70,000 albums — from world-psych to classic indie rock to electronica's darkest corners — available for high-quality download. Reasonable subscription rates, reliable recommendations, user playlists, reviews, and columns by online crit's finest — Pitchfork, Flavorpill (back pat!), AllMusic, and beyond — seal the deal. -Todd Goldstein

Drownedinsound.com

London's Drowned in Sound offer up daily news, reviews, and previews of UK acts not (yet) picked up by Stateside media, as well as a refreshing POV on international indie acts — not to mention that charming way of spelling! -Leah Taylor

Saidthegramophone.com

One of the first and most consistent MP3 blogs humming along on the Internet, Said the Gramophone has been posting noteworthy tracks and blurbs on emerging artists for just over two years. Its wide range of music and daily updates make it a site worth stalking. -Leah Taylor

Looserecord.com

The new kids on the e-block at Loose Record care about your music taste, or (gasp!) lack thereof. With their site and biweekly mailer, they offer a more single-mindedly rock-oriented option than Pitchfork or PopMatters, providing informed and often witty reviews and opinions on indie shows, albums, and artists. -Leah Taylor

Snobsite.com

The Rock Snob's Dictionary: An Essential Lexicon of Rockological Knowledge, David Kamp and Steven Daly's immensely enjoyable lexicon of tongue-in-cheek yet spot-on musical reference points, spawned Snobsite.com. The site's learned bloggers elevate the science of snark with posts on esoteric masterpieces, heinous artistic missteps, and the outing of closeted fellow snobs (Harry Potter's Daniel Radcliffe! Who knew?). -Todd Goldstein

Bleep.com

Though the iTunes music store grabs a lion's share of the accolades for online downloads, Warp's Bleep.com offers a pleasantly niche-y alternative, giving electronic-music fans digital access to the label's vast back catalogue, along with releases from tastemaking labels such as Thrill Jockey, Leaf, and Lex. -Colin J. Nagy

Gabba.cc

Gabba has defied the status quo of music blogs, instituting a form of interactive, merit-based democracy in the medium. Contributors post obscure tracks, ranging from raucous dancehall reggae to dreamy ambient, gaining points for how well the tracks are received by fellow readers. -Colin J. Nagy