This are my favourite sites at the moment:

AllMusic
Rateyourmusic.com
Counting out time
Tigersushi (dance)
World of triphop
Pop instituut (dutch bands)
Muziekweb (If you live in the Netherlands than you can rent almost all Music by Muziekweb and it is sent to your local library)

I'm missing some interesting sites?

<edit>links updated</edit>

(E)Zines

English
Buddyhead !
Pitchfork !
Delusions of Adequacy
cross my heart with a knife !
Collective Zine
Lambgoat
Posionfree
Punknews
Bettawreckonize

German
Beatpunk !
Die Bluemchentapete !
Ox Zine
Waste of Mind
Mainstage



Misc. Stuff
Meu Dia de Morte !
What the heck *is* emo, anyway?
How to dress emo?
Emopunk
Stars and Skulls Club

Stuff I personally enjoy a lot because it's well written, personal, fun or just 'different' is marked with a '!'.

Thanks dev0,

I like the album reviews on Epilogue Music.

I like DMusic...
They have some nice music and articles as well.

LIF

I have updated the links above.
Who has some other interesting websites?

Chudah's Corner for game music info and reviews.

http://www.discogs.com/ a user-submitted database (vynils, singles, ltd editions, rareties...)

Updated my post too.

Kill From The Heart

the roots of hardcore/punk, discography's , bio's etc.


Dementlieu Punk Archive

another site covering the early years of hardcore/punk


SkatePunk.net

the name's self explanatory... i think


brainwashed

a good resource for industrial/avantgarde/neo folk stuff, home of people like Throbbing Gristle, Death In June, Current 93, Nurse With Wound etc.

www.metal-archives.com

best metal resource on the web, even underground bands, has discography, pictures, user reviews, plenty of info.

http://rige.net/
hard/terror/speed-core