Skele is the Unity extension that helps developers to do animation and cutscene authoring stuff with their rigged characters right inside the Unity Editor;
Unity's importer for model files is good, but it would be better if we could make animations without leaving the Unity editor.
Furthermore, it would be much easier to manage and control everything if we could make cutscenes while make character animations inplace and integrate all the fx/sound/gui/trigger stuffs on ONE same timeline.
Just put the character in your scene, pose it, animate it, direct the great scene, lead it on the destined stage.
If you feel interested and want to know more details, have a look at Knowledge Base with all the videos/Demos/manual, see what you can achieve with it.
Skele is composed of two systems,
The Bone Manipulator (TBM) and
The Cutscene Director (TCD).
TBM is made of editor tools for animators to make character animations.
TCD is consist of editor tools and runtime scripts for developers to make cutscenes and prefab-actions.
If you want to see some examples, take a look at the WebDemos in this site