I discovered a link from Scott Kelby’s blog to a new sort of portfolio gizmo called Exposure.So
It shows full screen sized images in a sort of blog post. The individual images can be up to 15Mb each, easily large enough to fill a 30 inch monitor browser page. I created a free sample here
You can have 3 free ones and after that there are various paid options if they work for you.
Impressively large I think.