Blender 2.5 tips

http://www.blenderguru.com/whered-that-button-go/

Recalculate Roll

Recalculate Roll = Ctrl + N.

Add Bone

Add Bone = Shift + A

Roll Armature Bone

Roll Armature Bone = Select bone in edit mode and hit Ctrl + R.

Scale Armature

Scale Armature = Alt + S.