You can create a free Mercator projection map at this site
http://www.aquarius.geomar.de/make_map.html.
[Edit by JaxWeather] Above resource found to be unavailable on Sep 11, 2010 and possible replacement located at:
http://woodshole.er.usgs.gov/mapit/When you've created the map, you'll need to capture the map image from your browser into a file on your hard disk. Then very carefully crop the borders off it to create the map image for use with MML.
If anyone knows of any other good sources of free Mercator maps please email 'maps
ATweather-watch
DOTcom' and we'll add the information to this FAQ. (Replace the two bold words with @ and . to form the full email address).
There are a couple of ways of creating Mercator maps using commercial applications from other suppliers. For example:
1) For satellite maps you could try GeoSatSignal at
www.satsignal.net which appears to have an option for converting the standard downloadable sat images into Mercator format.
2) For weather maps, you could use Digital Atmosphere
http://www.weathergraphics.com/da/ which can now produce Mercator maps.
I use both of these applications and find them very useful pieces of weather software.