DasBlog – the weblog engine this site is running on – allows extensibility through macros. You’ll need to use them as soon as you want any additional dynamic content on your site. (The ads you can see at the bottom of the right side bar are an example of a macro which I’ve recently updated to make the ad selection a little more advanced.) The documentation doesn’t mention their development at all therefore the following post by Vasanth Dharmaraj is probably the best source of information available on it. It actually discusses everything you need to know to get going. Make sure you read it before trying to write your first macro.