Blog as novel. Entire novel as a series of blog posts. Could be framed as the found text of a journal, such as the Red Book of Westmarch. Tolkien Gateway: Red Book of Westmarch
Blog as novel, extreme version. As above released in real time. No going back to adjust plot points. What you wrote is what you work from going forward.
Blog as epistolary novel. Two, or more, blogs that interact with each other.
Blog as journal. Main segment of story is a traditionally-structured narrative. Blog posts are used for characters to speak, as with journal entries.
Blogger as character(s). Character(s) goes through their activities of daily living. Each chapter ends with blog post(s), that might or might not bear any reality to what has happened in the storyline.
Blogger as main character. As above, with the addition that character’s activities of daily living are to write a blog. The two threads of the story are the blog and behind-the-scenes of said blog.
Onwards!
Katherine
Virtual Brush Box 
I particularly love the idea of blogs talking back to one another. This has given me a lot to think about. Thank you!
Which approach do you think you will use for your novel?
Joan
janpriddyoregon. I look forward to seeing what you do with the idea.
Joan. For that matter I look forward to seeing what I do. Be as much of surprise to me as to the rest of you.