Sometimes more than just connection strings need to be stored to a settings or configuration file of some kind. If you are building a mult-tier application and your project is a class library with no run-able code, you can't just throw settings into an app.config file. Likewise, you wouldn't want to put your tier-specific settings in a different project just because that project contains the output (and the app.config).
A simple way around this problem is to create a settings file for your project. To do so, right click on your project and select "Properties"
Navigate to the "Settings" tab and click the link to create a new settings file
Add the application specific parameters to your settings file via the designer. Save and rebuild your project.
To use your settings, reference them via the following syntax:
Properties.Settings.Default.MySetting
Enjoy!