3 different blogs in my mind ...
The diary type blog that are open to general posting ...
The search engine honey trap blog filled with links and hey word rich (fake blog)
And sits like
http://www.kblogger.com that sure do have search engine relevance but also share valuable information and CAN be posted too (anyone can post comments to any blog and they can be answered and bounced back and forth). Check the bottom of each entry and you'll see the comment link.
h34r: