I think that there are a number of factors that make a blog popular, but there are a few characteristics that I think are more prominent than others. First off, I like to see personality come through in a person’s blog, but at the same time the subject matter has to be relevant to the majority of the audience. If the blogger speaks about things that only he and a few others may know about, then the blog becomes lame and hard to comprehend, which makes for a not-so-popular blog, in the ever-expanding blog world.
Anther characteristic that I look for is validity on the bloggers page and feedback from other people. If you have a lot of feedback on a person’s blog, then obviously their blog is pertinent and therefore popular. I don’t necessarily think that a popular blog has to have overwhelming numbers of people who respond to the blog, but it does have to have a good core of people who respond everytime there is a post. This creates validity in having a popular blog.
A great example of this is a blog created by a fan of celebrities in which a simple website became an overnight sensation and now is viewed thousands and thousands of times a day. Perez Hilton’s perezhilton.com is a gossip blog that has made him into a celebrity of sorts as well. I really don’t like him personally, but if it is a popular blog you are looking for, then this would have to be considered one of them because of the huge number of loyal followers who post on a regualr basis.