Allow Javascript in Posts and Pages is a plugin by Hit Reach that allows Javascript in posts and pages adds the functionality to include Javascript in wordpress posts and pages by adding a simple shortcode [js].code.[/js]
This plugin strips away the automatically generated WordPress paragraph and line break tags but still allows the addition of your own paragraph and line break tags by using [p] and [/p] or [br/] or [a href=’void(0)’]link[/a]
Download and info: http://wordpress.org/extend/plugins/allow-javascript-in-posts-and-pages/