What are some possible options for a GUI to manage style and map file for MapServer.
I am interested in all solutions, QGIS plugin, ArcGIS mxd or MapInfo workspace converter or else.
I was looking for exactly the same thing some time ago. I did find some tools, but most of them are out of active development and only support old version of mapfile syntax. But anyway here is what I've found.
Sribe UI: this is a very new project and looks promising (only support mapserver 6.0+). It is under active development but still in early phase, they've just released 0.1 version.
MapFile viewers: There's a QGIS pulgin available
mscompanion: A GUI WYSIWYG Mapfile editor for MapServer running on Windows. (Very old, untouched for several years, and the latest version is compatible with mapserver 5.4.0)