You'll have to search the DHTML sites (and JavaScript, but they aren't quite as nice for this purpose) to find a script that suits your design ideas.Here are a couple to get you started:
http://www.webreference.com/dhtml/
http://www.24fun.com/
That second one has several very annoying pop ups, but their scripts are good, and worth the effort for a scripting novice to close those annoying advertisements.