Just put in a new function to display random 'blog entries.
It's not (right now anyway) available on my home page, but if you go to any of the 'blog pages that list the monthly archive links, right above them is a new link labelled random.
This link will, duh, display a random entry from the appropriate 'blog.
Here's a link to a random entry in the main 'blog just so you see what I mean.