From BlenderWiki
Display
Grid Floor
(to be written)
X Axis
(to be written)
Y Axis
(to be written)
Z Axis
(to be written)
Outline Selected
(to be written)
All Object Centers
(to be written)
Relationship Lines
(to be written)
Textured Solid
(to be written)
Split region in 4 parts
(to be written)
Lock
(to be written)
Box
(to be written)
Clip
(to be written)