I’ve been doing a bunch of experiments with the new Facebook iframe page tabs and have cooked up a Facebook Tab Manager plugin for WordPress, which works pretty well. This plugin lets you compose and edit content for your a tab to appear on your Facebook business page (or campaign page or nonprofit page) from within WordPress. I use custom post types to treat Facebook tabs a just another kind of post, and the content can be integrated with other plugins using WordPress Shortcodes.
The content is displayed in a very simple template with none of your site’s normal navigation, etc. That makes it easier to make it fit into a Facebook layout. I provide some default styles, but you can also add custom CSS on a per post (or per tab) basis.
As part of some promotional work I’ve been doing with cloud database company Caspio Inc., I’ve also created custom tabs you can see on the Caspio Facebook page and ExpressDB Facebook page. These demonstrate how data entry forms and database reports from Caspio’s online database products can be embedded in a Facebook page.