>I use app.config to hold connection data.
>Switching servers during development is tedious.
>Since I can't include comments in the app.config, I have to type all the credentials each time I switch.
>I'd like some way of commenting/uncommenting credentials, dependng on the server or db I want to use.
>Any ideas?

Couple of solutions here: http://stackoverflow.com/questions/8082662/how-to-select-different-app-config-for-several-build-configurations

Haven't tried SlowCheetah but seems to work in the same way as the built-in transforms in asp.net for web.config. If it does what it says on the tin I'd go with that.
Next best is using the 'after-build' approach mentioned in the same post. Downside of that is that you need to keep the whole of each alternate app.config up to date which can be a pain to maintain......