Yes - it turns out there is. It is a bit tricky, but there is a way to get the same graphic file that the program uses.
Load up the RouteGadget page that you are interested in in your browser. Save the web address.
You now need to look at the underlying html for that page. Either right-click and use "View Source", or try saving the page using "Save As" from the file menu. All browsers should be able to do this, but the mechanism may vary.
In the source, search for the string <param name="karttaid" value=
The value in that line will give you a number, something like "28" (I'll use 28 in this example).
Assuming that your original RouteGadget page was at this address:
http://routegadget.bigfootorienteers.com/cgi-bin/reitti.cgi?act=map&id=31&kieli=
Then the map image will be at this address:
http://routegadget.bigfootorienteers.com/cgi-bin/kartat/28.jpg
Right click or use the "Save As" command to save the image.
(Many thanks to Scott Collier who posted this trick on NopeSport)
