Just came across this : http://converter.mygeodata.eu/
Its free and it seems to convert to and from a quite large number of vector and raster formats.
According to the statement on their site:
MyGeodata Converter allows you to read and write from/to a huge number of CAD and GIS formats – both vector and raster. MyGeodata Converter is more than only simply data converter! In contrast to common format convertion MyGeodata Converter allows sofisticated data processing during conversion. MyGeodata Converter also can be used as a powerful tool for collective data and attributes processing.
Haven’t tried it yet but it sure worths a try.