Create Splash Pages and Promotions with Free jQuery Plugin, Meerkat, created by Jarod Taylor. Meerkat, depending on the options you have set, will slide or fade in from the top or bottom of the browser window and remain in its fixed position while the rest of the page will scroll normally.
Whether it’s used as a simple promotional tool, a roost for advertisements, or even as an alternative to a splash or entry page; Meerkat is unobtrusive, cross-browser compatible, and degrades gracefully if Javascript has been disabled.
Website: http://jarodtaylor.com/meerkat/