Jenny is in a Bad Mood

More classic styled Japanese Vocal Pop, Rock and Psyche
http://jennyisinabadmood.blogspot.com/

Pachinko Overdrive

Loads of Homemade Mixtapes from Japan
http://pachinkooverdrive.blogspot.com/

Rebel Japan Music

Japanese Rock & Indie
http://javandalism.blogspot.com/

Ongaku Tanoshimi

Japanese Lounge and Bossa. Dead but Alive.
http://ongaku-tanoshimi.blogspot.com/

Shibuya-Kei or Something

As the blog title says, international sounding 90's J-pop
http://shibuyakeiorsomething.blogspot.com/

The Vault

Japanese Music: Experimental, Electronic, Indie, Hardcore, Metal, Jazz, New Wave, Pop, Punk, Rock, Visual Kei. Picopop. Massive Blog.
http://voodoovault.blogspot.com/

NYU's Anime and Stuff

Lots of anime but also a ton of J-pop and Rock
http://nyu-anime.blogspot.com/

Lifer

A lot of great stuff here in various categories. Modern Shibuya-Kei, Prog, Rock, Power and Black Metal, Electronic, Experimental, Jazz
http://liferthereviewroom.blogspot.com/

Fatal! J n K Music

Lots of Japanese and Korean Pop and Rock
http://onlyjmusic.blogspot.com/

Tokky Dokiis

Japanese Pop & Rock, Visual Kei, and K-Rock
http://tokky-dokiis.blogspot.com/

Barbarism Begins at Home

Lot of great vintage (80's to current) Indie and Alternative with the occasional Hip-Hop and Electronic thrown in
http://lunchmatic.blogspot.com/

Naoridownloads

Japanese Pop + Indie - old and new
http://naoridownloads.blogspot.com/