I recently programmed a cool Javascript addon for Blogger.
Basically what it does is parse through you blog archive and select a random post. Then it puts a random text link to the post it selected. You can see it in action at the top of my blog:
Inkweaver Review - Book Reviews & Cover Art
Just refresh the page a few times and you'll see a variety of random messages about different posts I have done over the past months.
If you want the code, then visit my blog post:
Random post addon for Blogger - Inkweaver Review - Book Reviews & Cover Art