The secret to low-cost academic blogging is to make blogging a natural byproduct of all the things that academics already do.

• Doing an interesting lecture? Put your lecture notes in a blog post.
• Writing a detailed email reply? "Reply to public" with a blog post.
• Answering the same question a second time? Put it in a blog post.
• Writing interesting code? Comment a snippet into a post.
• Doing something geeky at home? Blog about what you learned.