wondermill

If you want to graphically display a random list of your posts with their featured image in the side bar, then this is the plugin for you. This plugin allows you to set the category IDs (or all categories) you want to pull the random posts from, the number of random posts to display, the maximum width and height of the featured image thumbnail, the widget title, and the colors of the surrounding box.

Random Posts with Thumbnails

Puts a list of clickable random posts with their featured image in your sidebar as a widget, this list is customizable.

James Harrison

macardam

The shortcode [arandomnumber] can be added to any post, page, or widget as many times as needed to display a random number. The number has a default range of 1 – 100, but can be changed using the min and max attributes, like so:
[arandomnumber min=1 max=10000]: This will output a random number between 1 and 10,000. (Like this: 8,014) 
[arandomnumber min=-500 max=-1]: This will output a random number between -500 and -1. (Like this: -232) 
[arandomnumber min=50000000 max=60000000]: This will output a random number between 50,000,000 and 60,000,000. (Like this: 56,449,060)
etc.
If you wish to disable commas, use the comma=no attribute, like so: [arandomnumber min=100000 max=999999 comma=no]. This will output a random number within the range without the commas, like this: 456245.

A Random Number

A WordPress plugin that displays a random number on each page load via shortcode. It truly is magic.

Random Posts with Thumbnails vs A Random Number