in the map viewer control,
Mapviewer1.AddLocation(location) // adds a pin to map
does anyone know how to change the marker of the pin from one color to another, (it defaults is red)
Changing the icon property to a pin of your choice should do the trick I believe. In other words you will have to draw your own pins for each of the colors you want and set the icons accordingly. Check the docs for more info.
but please use one webPicture per color and avoid sending 100 pictures to browser for 100 icons…