When I need a name for a new class that extends behaviour of an existing class, I usually have hard time to come up with a name for it.
For example, if I have a class MyClass, then the new class could be named something like MyClassAdapter, MyClassCalculator, MyClassDispatcher, MyClassParser,...
This new name should of course represent the behaviour of the class and would ideally be same as the design pattern in which it is used (Adapter, Decorator, Factory,...). But since we don't overuse design patterns, this is not always the solution :)
So, do you know for a dictionary or a list of common words, that we can use to represent the behaviour of the class, containing a short description of the expected behaviour? Some examples: replicator, shadow, token, acceptor, worker, mapper, driver, bucket, socket, validator, wrapper, parser, verifier,...
You could also look at this list as a cheat sheet for metaphors, with which you can better understand your problem domain.