http://amorticiando.blogspot.com/ : tons of death and black metal, a bunch of classic essential bm albums.
http://punknotprofit.blogspot.com/ : punk albums galore.
http://jazzearredores.blogspot.com/ : jazz albums.
http://metal-ist-the-law.blogspot.com/ : more metal, more obscure stuff.
http://zerogsound.blogspot.com/ : world music
http://citiesonflamewithrockandroll.blogspot.com/ : mostly old japanese psych and prog but features other countries too.