Brain Pulse Music

Former Ghost member Masaki Batoh released Brain Pulse Music, a collection of prayers and requiems for the victims of the earthquake and tsunami, featuring traditional instruments as well as two brain-controlled electronic devices called BPM.
The album is out on Drag City and the machines themselves are on sale as well for $699.
There's a nice article about the project on Wired. Proceeds go to the Japanese Red Cross.


Project Fukushima!

Project Fukushima! is (mainly) a free music festival which will be simultaneously held in Fukushima and locations all over the globe on August 15. The organizers -- experimental music hero Yoshihide Ôtomo, Michiru Endô (from punk band The Stalin) and poet Ryôichi Wago -- also curate a series of DIY Hearts released recordings featuring artists such as Seijaku (trio featuring Keiji Haino, Yoshimitsu Ichiraku a.k.a. Doravideo, Mitsuru Nasuno), Tatsuya Yoshida (from Ruins), Ryûichi Sakamoto, and a jam session featuring Nanao Tavito, U-Zhaan and the dearly missed Rei Harakami. Here is the list of available titles.
Benefits will be used to finance the festival.

Recorded For Japan

R. Stevie Moore, members of MGMT, Kurt Vile, Ariel Pink's Haunted Graffiti and more are featured on charity compilation Recorded For Japan. Sales proceeds will go to the Japanese Red Cross. Here is a preview :

LA♥JPN♥LA

The "LA♥JPN♥LA" compilation is a collection of exclusive tracks from artists in Los Angeles and Japan showing their solidarity in supporting the earthquake victims of Japan.

Featured artists include Dâm-Funk, Carlos Nino + Miguel Atwood-Ferguson, Ras G, Inner Science and 23 others. Details here.
 
Available through iTunes worldwide (you can also preview it on Bandcamp). Proceeds go to the Japanese Red Cross and Civic Force.

Help Japan

Help Japan compiles remixes (Radiohead, Regina Spektor, Matisyahu) and original tracks in genres spanning folk, chilled instrumental electronica, dubstep, klezmer, indie, performance poetry and more. It's available on Bandcamp at the starting price of £2 and will later be released as a CD. You can also name your price and receive physical bonus material if you donate more than £15 (an iPhone app, videos to download, merch, CDs... the more you spend, the more you receive!).

Curator Steve Paul, who also wrote an important part of the music presented here, explains about the project in this Raised By Records interview. All proceeds going to British Red Cross Japan Tsunami Appeal.

Plus Records

Techno producer Shin Nishimura's Plus Records label released a two volume charity compilation featuring Dave Tarrida, Hiroshi Watanabe, Salmon and many more. Available through Beatport (vol.1, vol.2) and Juno Download (vol.1, vol.2). Benefits go to the Japanese Red Cross.



Ich Danketsu

German electro-pop label Megapeng released Ich Danketsu, a free compilation encouraging listeners to donate to GlobalGiving. Featured artists include Applehead, Kania Tieffer, Trippple Nippples and more happy-go-ravey bands.

COMPassion

Orange County, NY based Parrot On A Porch Records released a charity compilation entitled COMPassion, featuring indie pop/rock/emocore artists such as Jonah Matranga, Codeseven, Chamberlain, Mourning District and more. 
Proceeds go to Relief International.

Something We Can Do

Something We Can Do features 15 previously unreleased tracks from some of the most revered names in the world of drum & bass and dance music today (notably Makoto and DJ Marky). Available on iTunes, Beatport, Bandcamp, Soundcloud. 100% of the profits from the sales of the album will be donated to the Japanese Redcross.

Japanease

Music distributor Wordsandsound curated Japanease, a colossal compilation of electronic dance music featuring Prins Thomas, Technasia, Elektro Guzzi, Anja Schneider and a ton more. Almost half of the 138 tracks were previously unreleased. Available as 3 packages or separate tracks, on almost every download platform one can think of (iTunes, Juno, Boomkat, Amazon...).
The entire income of sales will be donated to the area of Sendai/Miyagi through the German Japanese Association in Hamburg.