This is perfect for blogs. Say you have a long post, someone reads it. Then leaves. Google considers that a Bounce.
Theres the article. Essentially, you need to push an event to google, in this case its "read" - so they can avoid a bounce rate. Obviously, people can set whatever timer they want. However, this should work for most.
So you could simply allow us to insert any line of text as part of the settings, or you can get fancy and build the trackEvent and allow a field for the event name, and the time. etc...
But all that has to be added to the code to limit bounces would be this:
setTimeout("_gaq.push(['_trackEvent', '15_seconds', 'read'])",15000);