VGMap is a library that allows designers, developers, and mapping geeks to overlay data on top of Google Maps in a richer way than is possible using their standard system. The Google Maps API enables point and line data on their maps in the form of markers and polylines, which has yielded a lot of great mashup applications, but precludes its for more sophisticated GIS applications. Flash technology, on the other hand, provides vector drawing, as well as well-worn interactive and animation functionality. This VGMap library is simply the glue between Google Maps and Flash, which we hope will help to provide baseline technology for building open, web-based GIS applications using Google Maps as the base layer. The first application we developed with VGMap was an interactive New York city Subway Map.