You can get lap dance it displays a pop up when someone clicks to exit your site. It's available in the download section of bhw.
+Rep Thanks, I'll add that too, still interested in an automated popop plugin An example would be like this BHW members site: http://www.seocompensation.com/ It automates a plugin after 3-5 seconds.
Sorry for digging old thread but in case anyone need a popup plugin: http://wordpress.org/plugins/bueno-gato-free-popup-creator/