affbuzz.com is an aggregator of all the affilate and internet marketing blogs. It's a relatively young industry, and the content creators are young as well. I expect you are seeking deeper intellectual content rather than how to make a quick buck, but you should find it interesting nonetheless. Searching through some of the blogs will find you many intriguing case studies, trends, and unexpected marketing avenues. The most popular ones are on top.

Among those, here's some with more case studies and content vs. just selling you something, talking inside baseball, or 'motivation': cashtactics.net, rileypool.com, mrgreen.am, finchsells.com.

A lot of the best content in this area exists as "stickies" on certain forums . . .

The general consensus is: keep looking. Don't buy ebooks. The best info is freely available but can be buried in mounds of crap -- usually paid content is the way to cut through the crap, but not in this arena (in 98% of cases).

All friends and acquaintances:

http://reactionwheel.blogspot.com/

http://www.cogmap.com/blog/

http://mikeonads.com (sporadically updated but good)

http://ecpmblog.wordpress.com/

I write a blog about "digital strategy" (the ad industry insider-speak for what you're talking about) at http://www.joshklein.net. Most of my posts are about big brand strategy from inside an advertising agency, but I also think startups should know about many of the same things.

I subscribe to adexchanger's news letter which covers industry trends and what-not.

There is a lot of noise, but good coverage of the big players / industry level news.

www.adexchanger.com

Rkgblog is a great resource for anything search-related.

Rob Walker's stuff is very good.