The Y's series in Japan has been going strong since the 1980's and one of the aspects that made it famous is its very memorable music. The soundtrack for Y's Online, the new MMO of the Y's series, has just been released for free as covered by Massively.
Go check out the free OST here!
Update: Unfortunately, one of the tracks "Blood on my hands" seems to be missing any music and is completely silent from the single downloads and the OST compilation even though you can download it. Hopefully they'll correct it shortly.