Andrew Johnson asks What makes a good blog post? I can see good advice in all his points with the exception of number 9 which I think is simply not applicable to many areas of the online.
I know that my other blog In a minute Ago which is aimed at the quilting and crafting community online it would not work. This niche community has its own dynamic and many of the social norms that I see in quilting and stitching groups are transferred online. I know many readers would simply turn away not only from one particular blog but blogging if it became OK criticise someone simply to create a bit of buzz.
In the online crafting community if you want to create a buzz writing a good tutorial on how to do something, making an exceptional piece or starting a creative challenge that people can join in on are ways to draw attention.