Mark-k

Once a day wordpress deletes all trashed items which had been in the trash for more then N days, where N stands for the value of EMPTY_TRASH_DAYS constant which may be defined in wp-config.php file.
This plugin presents a different way to control the number of trashed days. Instead of manually editing wp-config.php which is usually not convenient and somewhat dangerous, you can set the number of days in a settings page. 
In addition there is a tool to empty the cache from Items older the a specified number of days.
Usage: 
Get to the settings page via the menu “Options” >> “Empty trash” 
Get to the delete trash tool page via the menu “Tools” >> “Empty trash”
Network considerations: 
The plugin was not tested in a network installation, but it should work gibing the individual site admin a control over his trash which is possibly different then other sites on the network. 
The plugin do not have network wide settings
Important: 
For better or worse the plugin employs exactly the same deleting algorithm used by the wordpress version running the site.
Limitations: 
The plugin will not be able to function well if you have EMPTY_TRASH_DAYS set in your wp-confing.php

Trash emptier

Provides a configurable control over the trash emptying algorithm wordpress uses without changing wp-config.php

mikehealy

If you use the WordPress admin area on a mobile device, or have cats sometimes walk across your keyboard it can be good to have a fail-safe confirmation before permanently deleting posts from the Trashed items. 
This plugin adds simple JS to the admin area to do just that.

Trash Fail Safe

Require confirmation before deleting items from the Trash, or emptying the whole Trash. Protects against accidental clicks.

Trash emptier vs Trash Fail Safe