Masdi

This is a simple plugin to track which your link website is broken and not found.

Not Found Tracker

A simple plugin to record the activity of your website address that can not be…

brohar

PF404 for PetFinder will replace your generic 404 page and replace it with animals available for adoption. You can select between dogs, cats, birds, reptiles, horses, small and fury, and even barnyard animals. Configure the page heading and contents of your 404 pages within the plugin settings page. 
This plugin does require a free PetFinder API key. 
This plugin or plugin developer is not affiliated with PetFinder.com.

PF404 for PetFinder

Overrides your 404 page template and shows dogs, cats, and other animals in need of new homes and available for adoption.

Not Found Tracker vs PF404 for PetFinder