Why do you blog?

Mostly for selfish reasons. I needed a way to keep track of software development over time-- whatever I am thinking about or working on. I can research things I find interesting, document my research in public with a blog post, then easily find and refer to these blog posts later. Hopefully other people will find these posts helpful, relevant, or interesting. I firmly believe that blogs are a two way conversation, so I welcome email and comments-- as long as they're on topic, more or less.