Casper's Flyin' Call-to-Action

This plugin enables you to add a bar to the bottom of the page (left, right, or centered) to act as a call to action.

It slides open when you click it, revealing more information. You can even include a form right in the slide out.

Alternatively, you can put the call-to-action on the left or right of the page, not at the bottom.

It also slides open when clicked, revealing an important message or further steps the user may want to take.

You can find settings for this call to action, including background and font colors, under Appearance -> Fly-in CTA.

As shown here, there are several powerful settings. Not only can you control where on your page the CTA sits, you can determine which pages to have the item show up on. You also get a full WYSIWYG editor where you can add media and forms. You also have the option to turn it on and off without having to deactive and reactivate the plugin.