SlideDeck is a Jquery-compatible add-on (adaptable to any site) as well as a WordPress plugin that allows you to organize content, images and more into professionally-designed sliding decks.
View some cool examples:
There are two versions available:
a) Free version - fully working (it doesn't have vertical sliding options, it carries a link to slidedeck and has no pro support)
b) Pro - $99
More info on pricing: http://www.slidedeck.com/pricing/
Find out more: http://exclusive.slidedeck.com/ub-slidedeck/
(Reviewed by Robin Good)