I actually tried having separate blogs for each my interests at one point, in an effort to keep things "focused." I found that I ended up not keeping any of them up-to-date. None of them alone generated enough interest for me to keep writing for them. A few months ago I combined both blogs (one was personal and one was professional) into one. The new blog is much easier to write for because it's "whatever I feel like."

A lot of professional advice on blogs is to "keep them focused" and only write about one topic. The more I read, the less I agree with that. If I'm reading a technical blog, I still want to know where the author is coming from and what experiences they have. It helps me connect with the author and encourages me to continue reading the blog. Posts like "So I need Your Help" and "I Got Pay It Forward-ed" do that.

I also agree with Jesper. This is your blog, and if there's anywhere where you should be able to write whatever you want, this is it.