In ASP.NET 1.1 i've used appSettings file="DevSettings.config" to specify an external file that contained custom application configuration settings. DevSettings.config wasn't included in the project and was not copied to the production sites.
In VS 2005 all files are included in the project and "Publish Web Site" command copies to production all files , including those that I don't want to copy.
But there is a simple solution - change the name of the file DevSettings.config to DevSettings.config.exclude.
And the file will not be copied to the target site -exactly what I need.