I just started listening to jpanese music again, but I still don't own any J-Pop CDs(The Cowboy Bebop CD that came with the DVD boxset doesn't count, because that's mainly english), but I found this great internet raido station called Japan-A-Radio that plays a bunch of J-Pop and anime music(they're playing the english version of "Come Sweet Death" from End of Eva right now. I know it's not japanese, but I really like it ) and they also play Hikaru Utada's japanese version of "Simple and Clean" from Kingdom Hearts. My two favorite songs right now are "Cinderella Story" from Tenchi Muyo! and "Lights brought the future" by Globe.
I recommend checking out this site if you haven't. It's really good, and the quality is great! A dial-up version of the station is available as well though.