Most of it sucks balls, but here are some good artists + cool songs:

Tokio (YouTube - [PV] TOKIO - Sorafune, YouTube - TOKIO - SeiSyun)
Asian Kung-Fu Generation (YouTube - Riraito)
Dragon-Ash (more like j-rap, but still awesome: YouTube - Dragon Ash - Shizukana Hibino Kaidan Wo, YouTube - Dragon Ash『Los lobosã€)
SADS (YouTube - SADS - Boukyaku no sora PV)
Utada Hikaru (YouTube - Utada Hikaru - Exodus '04 (LIVE), YouTube - Utada Hikaru - Beautiful World)