I really like the script used on this page:
http://www.1stwebdesigner.com/wordpress/wordpress-themes-for-bloggers/
the popup shows after some set time but also earlier if a user moves the mouse cursor up to the header of the web browser.
from psychological point of view it’s great because it focuses my attention just seconds before I leave the page (as most users move the cursor up to click the close button in upper corner of page)
can you add a solution like this in your popup banner? thanks in advance 🙂
Lukasz