If your newsletter was read by 100 CEOs of Fortune 500 companies, I doubt you would have a hard time finding advertisers.
Social network "junk traffic" is not particularly valuable. You would need millions of page views just to get in the door of major media buyers.
Adsense is a different story - you don't need page views to get started.
if you have a high value niche with targeted, quantifiable traffic you can get that maybe as high as $50/cpm on a well marketed site (read: you have ad sales people or you're cramming the site with ad channels.)
This guy http://www.johnchow.com/make-money-on-the-internet-april-2007/ has grown his blog to 250,000 page views, crammed it with every kind of contextual ad you can think of, is a compelling writer with great content. He's at $50/cpm. Of that, 40% comes from a pay-per-post ReviewMe ad thing, so his ads are generating about $30cpm.
So you can put adsense on the page, but you won't make any money. and you're a ways off from doing banner ads.
Basic summary: if you can start a blog/site geared towards users who probably have the Alexa toolbar / Firefox SearchStatus Plugin installed, you can reap much higher CPMs.
1) How targeted is my audience? 2) How well can I describe my audience? 3) How many ads do I need to sell to justify the costs associated with selling ads (ad server, cost/time of setting up the ad server, salesperson, etc)?
"Getting" advertisers is an active process (i.e. sales) for most publications (online and offline).
You can always throw up some google ads in the meantime. If you have good cpm/ctr numbers from google it will help.
Does anyone know if Google cares if you run other networks' ads on the same page as AdSense ads? I think I've seen people do this.
http://www.johnchow.com/google-updates-adsense-tos/ http://www.johnchow.com/adsense-intellitxt-together-at-last/
Did you mean "does not care"? Being "all fair game" implies that you mean that Google does not care.