I collected a few raster overlays in a better detail level compared to the world-raster that is floating around the net.
The following regions are included:
Australia, New Zealand, Brazil, Canada-Alaska, USA and Mexico, Poland, Russia-Baltics and Finland, SE-Asia, Turkey, Southern Africa, Europe

To use the overlays copy the files from the corresponding folder in the archiv to the folder "raster" on your device - if not existing, create it.
When zooming out the street maps disappear and the raster overlay is shown.

Download the archive [Please Register or Login to download file] .

Finally managed to get detaild overlays with a reasonable accuracy.
The overlay will get a bit blurry once you zoomed out so the names can't be read anymore.
This is due to the fact that the image shrinks, so the detail goes down the drain - I can't fix that without creating seperate overlays for the zoom levels.
Creating low level zooms is virtually impossible as the accuracy decreases the low the zoom gets.
This is due to the source and neither Google nor Bing create accurate position data at those levels.

Created, detailed overlays:
[Please Register or Login to download file] created from OVI maps at zoom level 9
[Please Register or Login to download file] created from OVI maps at zoom level 9
The above overlays go to almost lowest zoom setting, after that it is only the normal TT map view.

[Please Register or Login to download file] this is a TT overlay of the whole world set to take over from the above overlay till lowest zoom.

You can adjust the settings for when to show the overlay:
At line 6 (zoom in) and 7 (zoom out) in the .sat file are the those settings.
The lower the numbers the earlier the overlay is visible.
0 means always visible, 65535 means "world view".

Downunder, i use Dirkroos his website for many years now.
And share my Overlays on TomTomHome. ( Grevelingen-West) and (Archipel) Grevelingen
I ask Dirk ( FB Friend) : Can you make the same prog. with BingMaps.
On the GE Map , the Netherlands is +/- 6 year older than BingMaps.
Example: [Please Register or Login to download file]
[Please Register or Login to download file]
The New Land at the Europoort /Rotterdam/the Netherlands

Pitty , his says NO.

Greets from the Netherlands , Kees /OneLover

Cleaned the thread and updated the first posting with working overlays in good detail for the USA and AU