I'm pretty sure every designer who reads blogs know about smashingmagazine.com. Great articles and fresh content keep me coming back to this site. I was even featured in one of their articles about effective Twitter backgrounds
Even though really I love print, web, and package design, I think I might love product design even more. I've always been a huge advocate enginuity and outside of the box thinking, so checking toxel.com every morning is always a must for me.
For a while I was checking 12-15 different design blogs every morning for new content. Then I discovered designfloat.com, which is essentialy digg.com for design articles.