There have been some new images using WMS servers added to the Gallery page. In the Gallery page, do a search (Ctrl-F in most browsers...) for National Map.
Here's my favorite as a direct link to the big image:
It's a big image, so it will take time to download into your browser. Once it does, Click on it to see it full size and then use the browser scrollbars to navigate. It shows an image that was spread horizontally over three monitors.
It's pretty wild to think that the Appalachian mountains really do form such swirly, almost fluid, ridges in Pennsylvania!