Adds a box in the sidebar that uses AJAX to update a list of new users every 5 seconds.
You can enable or disable it using the provided link. The default is for the box to be disabled. The setting is stored in a session cookie (setting is lost when you close your browser). The cookie is called 'nup_show_box'.
View the source. Its probably rather shocking... User:TheJosh/Scripts/NewUserPatrol.js
The links will take you to the edit of the talk page of the user - perfect for a welcome message.