Here’s just a little easter egg for you to play with:
?random to the end of your WordPress.com URL and it will redirect you to a random post on your blog.
You can link to that address like any other, either in your post or a widget.
I hope you have a very random Thursday. 🙂
Update: Based on a suggestion in the comments, I’ve added this to the admin bar so when you’re logged in and you hover over “blog info” the first menu item is a random post link.