I can understand why you want to create them, sometimes inner classes are an elegant way of solving a problem. In languages like Java, C++ and Python it is common practice. Java even has four(!) different types of inner classes and they can make your code a lot cleaner. In Perl just about anything is possible. Although it is common practice to have one class per file, it is not mandatory. Take a look at Inner Classes for ideas.

Cheers,

Harry