Your blog doesn't have to be about any one thing. That's what makes them so wonderful!
Some of us do have underlying themese -- mine is about my house -- but that doesn't mean I can't talk about other stuff, too. Much to my surprise, I found I'm not alone in my house issues and I'm having a ball with this!
I see you started one. I'm going to check it out.
You can check mine out in my sig line. The only rule: Just have fun!