Plenty of meme and viral sites have a random redirect option available to help their visitors find past content they may have missed (e.g. like the old StumbleUpon). Better Random Redirect for WordPress adds such functionality to your website. It lets you set a category for random redirects and choose the post type you would like to choose.
Better Random Redirect allows you to change caching time in the back-end. It also comes with a simple shortcode to add random redirect links to your site. This is a free plugin based on Random Redirect by Matt Mullenweg.