Yahoo Maps Embed
Yahoo Maps follows hot on the heels of Google Maps and Ask Maps by allowing users to embed maps in their own site. Yahoo MapMixer (currently in Beta) allows you to add an image to a Yahoo Map and then add the map to your own website via an iframe.
Here is the Roman Forum created by a user called travelkpr:
One nice feature of MapMixer is the Opacity slider, which allows you to change the opacity of the image overlay on the map. However compared to Google's MyMaps MapMixer is rather limited. With MyMaps you can not only add image overlays to maps but add placemarks.