I know this code has been around for a while, but Craig Andera's 'Last Configuration Handler I'll Ever Need' article is very useful.  He creates a class that implements the IConfigurationSectionHandler interface and uses deserialization to take the config file information and squirt it into a class.  It makes it simple to use a configuration section of a config file as well as making it easy to access these values from a class withoutout having to write any code to hook the class up.  Very nice.