logic-cafe
http://www.logic-cafe.com

Particular Sound by Frank Neumann:
http://www.particular-sound.de/

560 free royalty free loops:
http://www.loopartists.com

DSP-Ressources:
musicdsp.org

Kunz und Knobel:
Kunz & Knobel
www.myspace.com/kunzundknobel

Demos (Synth):
http://www.jrq.ch/demos/
http://www.pouet.net/prod.php?which=25948

DemoScene:
http://www.pouet.net

KVR:
http://www.kvraudio.com

rekkerd.org - free samples, loops, VST plugins and audio software news
http://rekkerd.org/

thisisnotalabel.com:
http://www.thisisnotalabel.com