AivarasFX

Plugin creates widget that displays one random image from current page or post attached images, or from any page or post set by ID. You can set size of image to display.
Displays a random image from post or page you specify. Plugin creates FX-Random-image widget. Use widget to add image to sidebar or add <code><?php FX_Random_Image($pageID, $link, $size); ?></code> function to theme. $pageID is page/post ID from there to take images, if $link = true adds link to image, $link = false no link on image, $size – image size (‘thumbnail’, ‘medium’ or ‘large’). Example <code><?php FX_Random_Image(1, false, 'large'); ?></code>

FX random image

Plugin displays random image from attached images to page or post.

pantsonhead

RandomText is a handy WordPress plugin that allows you to save, edit and delete categorized text, and inject random/rotated text by category into the sidebar (via widget) or page body (via template tags). The sidebar widget allows you to set an optional Title, and text header and footer. You could say RandomText picks up where the Text widget left off. Whether you want to display random/rotated trivia, quotes, helpful hints, featured articles, or snippets of html, you can do it all easily with RandomText.

Random Text

Store and display random/rotated text by category in sidebar widget or templates.

FX random image vs Random Text