There was a recent post about how clerics are only clerics and can't be anything else. There was a lot of good idea's as to what else a cleric can be. The idea that you don't let the class description limit you makes sense. This got me thinking about what other classes could be a cleric besides the cleric. I realized that both Bards and Witches would actually make decent clerics. Now I am wondering what other classes may be able to fill the roles traditionally filled by another class.
My challenge is to find a class that can function as another class. You have to be able to cover what people are expecting the original class to be able to do. Don't bother with the rogue as this has been the subject of too many threads. Your class should also have some advantages over the traditional class. Specific class features are do not need to be duplicated but the role they play needs to be covered. For example you do not need channel energy to function as a cleric, but you do need to be able to heal. Also ignore the source of any magic for this purpose.
Starting out I would say a Bard is able to function as a cleric. They have similar combat ability and the bard has access to cure spells. With his high charisma and skills he would make a better preacher than a cleric. Having perform oratory as a class skill is going to mean he is a better speaker than a cleric.