Ability to store selections Is there something similar to vertex groups for faces and edges? I find vertex groups incredibly useful for remembering custom selections I've made.

What I want to do is select faces or edges, and be able to reselect them later as easy as possible.
Sadly this feature will most likely never make it into the official release of blender. 

As CoDEmanX said, 


  It's not possible to implement it well in Python, as custom layer data propagates on actions like extrusion. So if you stored the selection state of edges or faces as a property of these elements, it would be copied over to the new elements when you extrude etc. 


Also it is important to notice that there are some selection difficulties that would come into play. in spite of all that, there is a proposal for such a feature, and it may become possible in the future.