Show Random Products has a widget that will show a random product (or products) in your store. It also has a shortcode to show the random products anywhere.
Shortcode usage:
[srp_random n=X cols=X cats=X tags=X]
where “n” is the numnber of products to show, “cols” is the number of columns. You can use “cats” to show products of certain categories (comma separated IDs). You can use “tags” to show products with certain tags (comma separated).