The Perfect Pop-up

"If you believe the likes of Jakob Neilsen and his supporters, nothing is more evil than pop-up windows. And in many ways, this is correct. Why? Well, we'll list the reasons soon enough, but in a nutshell it's because they are nearly always poorly implemented or simply not needed. This tutorial will show that, with the right thought, pop-up windows can be used without upsetting anyone - particularly the person browsing your site."

http://accessify.com/features/tutorials/the-perfect-popup/

Have a look, you might find this as interesting as we did.