Xform Modifier
Xform applies the basic manipulation handles that are rotate, translate and scale. This is useful as it can be applied to sub level objects such as faces and vertices. So by moving the xform modifiers center, you can rotate a face of an object about any point you like.

Simple apply the xform modifier to your object from the modifier drop down list, move the xform center to where you want it, then select the sub level object e.g. the face above, then select the xform gizmo and manipulate.
