tiny_singleton (rubygems): Tiny Singleton is a very simple implementation of the Singleton Design Pattern. Compared to the Singleton module in the stdlib, one does not need to class 'klass.instance' to get access to the singleton object, one can call 'klass.new' as usual. It is thus easier to add the Singleton Pattern to an existing class without changing the way the code calls it. 
Keywords: ruby|singleton-pattern