Splash Pop-Over

  Splash PopOver creates user friendly "splash" popovers in the same window as your normal page. This is nowhere near as intrusive as traditional pop-ups, and is more like an extension of your page. This is a much better model than normal pop-ups as it is far less annoying for visitors. It is therefore not blocked by any software.

This program is completely free and allows you to create an unlimited number of splash popovers. The program has a number of advanced features including display frequency options, scrollbar removal, time delay, auto close, and the ability to change the background color.