Mmmm check these out
*Hyde [J-pop] (Did some music for Blood+) Evergreen, Secret Letters, Hello, Careless Whisper
/\- Singer for L'Arc~en~Ciel that also does solo stuff dont know how to distinguish them apart...
*Maximum the Hormone [J-Rock] (I'm sure you know their death note into) Nitori BB Sensou, Black Yen Power G-Men Spy, Koi No Mega Lover
*Home Made Kazoku [J-...rap? hip-hop?] (Some random anime i think) Aikotoba, Joyride, Shounen Heart
*Tommy february6 [J-pop] (alter ego of a singer from another band) Candy Eyes Dolls, Candy Pop In Love, Dancin' Baby
/\- Singer for The Brilliant Green, also good tracks
Off the J Charts though...
*Sonata Arctica [Power Metal] (If you liked Dragon Force...) Misplaced, My Selene, Replica
*Eric Johnson [Instumental Rock (Guitar)] (Well known guitarist had a song in guitar hero) Cliffs of Dover, Manhattan, Desert Rose
And to Black~Rose, you might like Portishead imo its very evanescencey, and Seether is very Disturbediedy(?)
And i've got so-ho-ho much more just tell me your genre =)