Differentiating web.config between dev, staging and production environments

Anyone have any good tips on handling differences in web.config settings between environments? I’ve considered creating a ‘config’ folder in our source control system but outside of the web hierarchy, and having the deployment process copy the appropriate config files (web.dev.config,web.staging.config, web.production.config) into the web folder upon deployment. I’ve also seen posts on how to programmatically change the config settings (WCF endpoints, connection strings, etc) when the app starts.