Singleton allows me to have a sort of global object with a class/method interface instead of a plain global variable. Also, Class::WeakSingleton allows me to have a singleton that can expire when no more references to the object remain. It just makes for a handy way to pass data around sometimes. I use it for a place to stash some data that is used in a database wrapper and then re-used later deep in the database hook methods. It would have been difficult to put the data into the database and awkward to just have a global - so a comprimise.