I installed a piece of blogging software to the main site. The package is called wordpress and is a full featured, but free blogging software. I was debating on either writing mine own or using something that was precreated. I decided on precreated in order to be able take the power of others for templates.
Technically a blog can be created fairly simply. Create a database. Create a few tables and create a page to update the database. Once that is done, create a php page to parse the database. So, pretty simple, but things do get starting more complex when you want to add users and other fancy features.
I looked at bblog first, and than looked promising, but it had minor issues when installing and only supported on user.
I downloaded another one, but before trying that I decided to see what my favorite site used (blendernation) and they used wordpress.
It was easy to setup and had many features. So I used that. And all was well in the universe.