Urm.. I recommend these :

Chain (BACK-ON, Air Gear op)
Believer (BACK-ON)
Lost Heaven (L'Arc~en~Ciel)
glamorous sky (Mika Nakashima, NANA)
hitoiro (Mika Nakashima, NANA 2)
INNOCENT SORROW (arbingdon boy school, D.Gray-Man)
Daia No Hana (Yoriko, Black Cat op)
19sai (Suga Shikao, xxxHOLIC op)

That's all I can think of right now. Most of them can be found at gendou.com/amusic

If you want any PV, maybe you can check out this site :

http://www.getasianmusic.com/forum/viewtopic.php?t=3935