Soarport offers a free place to host large images (max 10mb) which can be embedded on a website rather like a google map.....apparently you can zoom and pan. This one's a mere 1.5mb to try it out.
Hey....it works, I'm impressed!!
NB...I had difficulties registering, so this one's an anonymous upload (and you need to register to manage your uploads and find them easily, if you're not registered you have to remember the tags you assigned when you uploaded....and my memory being what it is....!)