Robotreplay may be the latest in the category of tools that could possibly help you in fiding out what your visitors actually like about whatever you blog. The site offers to 'record visits to your site', including when readers read your stuff, where they click, how they fill in the comment form, and more important, where they get bored. And I believe it is that one thing, and that thing only is what you need to know, because if you can identify what bores people, you can stick an ad there ;).
It's pretty cool. The FAQ is a mustread before you sign up.