Three startlingly good marketing/SEO copywriting sources

I'm finding the creative in analytical ...
the balance of creative and analytical ...
something like that ...

Multi-Channel Merchant: Social Marketing Makes "Listening the New Black"
http://directmag.com/online/news/1011-social-marketing-listening/
http://directmag.com/mail/news/1014-successful-creative-crap/

Smashing Magazine: The Ultimate guide to A/B Testing:
http://www.smashingmagazine.com/2010/06/24/the-ultimate-guide-to-a-b-testing/

Copyblogger.com: All kinds of copywriting advice ...
http://www.copyblogger.com/content-marketing/
http://www.copyblogger.com/seo-copywriting/
http://www.copyblogger.com/keyword-research-introduction/