Note that National Geographic's Facebook page images link directly to nationalgeographic.com.

National Geographic | Facebook (http://www.facebook.com/pages/National-Geographic/23497828950)

How do they do that? I've not found it in the help section...

I think they've done this through the features available on a business Page:

Create a Page | Facebook (http://www.facebook.com/pages/create.php)

That's true Vin.

A page can be created on Facebook at no charge,but there are certain rates for promoting these pages, targeting specific networks and/or age groups.

I am aware of the promotion/advertising options but am not seeing where or how one can put a link with images.

The page I am working on is a business page: http://www.facebook.com/pages/Biblical-Archaeology-Society/45775980670

Rick,
Have you clicked on "promote page with an Ad"
It will take you to a page with options-

What do you want to advertise?
I have a web page I want to advertise.

I have something on Facebook I want to advertise:

Yes, I saw those... but after walking through them saw that they are about the ads on the right of the page... Is there a paid ad option that I've not seen that allows the business to link "main page" images to other sites?

Facebook Pages Insider's Guide (http://www.scribd.com/doc/8718197/Facebook-Pages-Insiders-Guide)

Maybe this could help you Rick?

EDIT::
Also these applications might help.
http://www.facebook.com/FacebookPages

Thanks! That site has some good stuff! I haven't yet confirmed exactly how national geographic did it, but it would not surprise me to find that either 1. they're paying for it, or 2. they're big enough to have some "pull" with Facebook to get it done outside the norm.