David,

By mentioning the dovetail plugin you have written & stating it was better than what was available you invited others to be interested. Many people have written plugins and shared them for free in the woodworking community, we respect and thank them for their generosity. Many people like Dave R who responded to you, devote many hours of their time in helping people to advance their Sketchup skills and woodworking. So if you have something to offer, great, but otherwise there seems little point in mentioning your plugin.