Whether you want an additional opportunity to promote your own products and services need to squeeze in a few more advertisements to site visitors, the technique of using Splash pages is all the rage.
I came across an excellent jQuery plugin (which I just couldn't keep to myself) for displaying these splash pages called Meerkat. Depending on the options set, the popup slides or fades into view from the top or bottom of the browser and remains in a fixed position while the rest of the page scrolls normally.
Those using Meerkat have a choice of providing a close option which closes Meerkat until the page has been reloaded, or a "dontShow" option, which closes the splash page until the browser session has ended, or for a set amount of days, depending on the options you have defined.
I would have included a screenshot but the developer Jarod Taylor has several demonstrations of the Meerkat plugin in action which are only a click away.
