List of Map Service Software

QGIS Mapserver || Open || GPL

Manifold IMS || Closed || Manifold

Sorry, I don't have any experience with this one. Just trying to help build a complete list.

One place to look is on the OGC web site - http://www.opengeospatial.org/resource/products/byspec and then select which version of the WMS spec you are interested in. I don't know how reliable the list is as it filled in by the developers of the software but I'd expect that if you went to the effort of writing a WMS then you'd register it there.

The list is divided into 2 categories, implementations and compliant products. The compliant products have been through OGC certification testing to ensure compliance. This is indicated by a green check mark and a certification test date.