You can boost up your affiliate marketing through your blogs.your earned commission will be higher than that of adsense.Also see commission junction.
Great CPA networks: MaxBounty, NeverBlueAds, Azoogle, Copeac. They all have easy "one field" submits such as email or zip code submits.
Adsense makes only about 10% of my income and i use it pretty a lot, but anyone who relies on adsense for more than about 1/3 of their income is a fool.
It would be a nightmare just worrying about registering and renewing domains, hosting, backing up, and moving the sites, let alone updating them with content. Whats funny is the guy only averages 11 dollars a blog a month. The fool could probably bring that average up to 100 dollars a month per blog if he got rid of 580 of the 600 and concentrated on 20 of them.
I use blog for make money and build traffic to my web network (include all of website and webblog) and use vary monetary plan such as Google Adsense, Affiliate program and much more.