I believe Goolge will be its own demise of sorts with the introduction of adsense and making links from blogs and blog content rank so highly. Why you ask? Right now there are millions of webmasters creating useless content just to kick up adsense revenue or try and get high SEO rankings with nothing more than a paragraph and a bunch of adsense ads. The internet is being flooded by directory sites, useless content, blog spam. When people create content targeted at getting high keyword ad placement does it really help out the end user? Does it really help out the advertiser? Probably not however I'm not sure I have a well thought out enough alternative. Adsense is by far the best program out there however if you've noticed the irrelavant results on google lately you'll know what I mean.
To me the keys to a good blog are:
1. Unique thoughts/content - The more unique your blog the more valuable it will be in the search game. Are you working on a special project? writing unique tutorials? reviewing unique devices? or are you just re-posting the same things 10,000 other bloggers just talked about?
2. Monitoring comments - are you active on your comment monitoring? All comments should be filtered if they contain a link or a link to a homepage. Random image (captcha) verification should be used for all posted comments. (I get around 1000 posts a day from poker sites but 0 make it through). Make sure comments are related to the topic being discussed.