The Generate From Usage feature in Visual Studio 2010 helps you use classes and members even before they have been defined.

You can use this feature to generate a stub for any class, method, property, field, or enum that you would like to use but not yet defined. The best part is that you can generate new types and members but without having to interrupt your workflow -- you need not leave your current location in the source code. You can use this feature both in your C# or VB.NET code. With this feature, you can generate stubs for classes, properties, fields, methods, or generate new types.

As an example, assuming that you have a class called Employee, you can generate a stub for an instance property for the property as shown below:

Employee employee = new Employee();
String address = employee.Address;

As and when your code references the undefined property called Address, just click "Generate Property Stub". You will notice that the property stub would be generated in the Employee class and the return type of this property will be determined from the context of the usage. The Employee class will now have the new property called Address of type String as shown below:

public class Employee
{
     public String Address { get; set; }
     //Other members of the Employee class
}

Generate From Usage is a great feature in that it promotes testability of your application's code.