From Monkeyfilter (like Metafilter only "with more bananas"), comes this comprehensive list of bloggers offering regularly-updated mp3 postings from their individual, idiosyncratic music collections... And virtually every genre is covered - from rock/pop, hip hop and reggae to exotica, bhangra, backmasking, drum solos and theremin... There's quite literally something for everyone, so you're bound to find your new favourite source of hard-to-find downloads somewhere in there.
(Graphic collaged from header images on Said The Gramophone.)