From BlenderWiki

This panel appears in the Editing Context panel group which is accessed using F9 or clicking button in the Buttons window.

Mesh

• Auto Smooth - Automatic smooth rendering (not faceted) for meshes. Especially interesting for imported Meshes done in other 3D applications. The Button Set Smooth on the Link and Materials(Mesh) panel must have been used on faces to make Auto Smooth work. The smoothing isn't displayed in the 3D Window, only in renderings.
• Degr 30 - Determines the degree in which faces can meet and still get smoothed by Auto Smooth.
• TexMesh: - Enter the name of another Mesh Object to be used as the source for the texture coordinates. Morphing-like effects can then be achieved by distorting the active Mesh. For example, a straight stream of water (as an animated texture) can be placed in a winding river.
• Centre - Each Object's Data has its own local 3D space. The null point of this space is placed at the Object centre. This option calculates a new, centred null point in the Object Data which may change texture coordinates.
• Centre New - As above, but now the Object is placed in such a way that the Object Data appears to remain in the same place.
• Centre Cursor - The new null point of the object is the 3D-Cursor location.
• VertCol Make - A colour can be specified per vertex. This is required for the VertexPaint option. If the Object DrawType is "Shaded", these colours are copied to the vertex colours. This allows you to achieve a radiosity-like effect (set MaterialButtons->VertCol ON). If the Mesh is "Double Sided", this is automatically turned off.
• TexFace Make - Assigns a texture per face. Will be automatically set when you use the UV-Editor to texture a realtime model.
• Sticky Make - Allows you to assign a texture coordinate to Meshes that are derived from the way the Camera view sees the Mesh. The screen coordinates (only X,Y) are calculated from each vertex and these coordinates are stored in the Mesh. It's as if the texture is permanently projected and fixed on the Mesh as viewed from the Camera; it becomes "sticky". Use "Sticky" to match a 3D object exactly with the Image Texture of a 3D picture. This option also allows you to create special morphing effects. If the image is already "sticky", the button allows you to remove this effect.
• Slower/Faster Draw - When leaving Edit Mode all edges are tested to determine whether they must be displayed as a wire frame. Edges that share two faces with the same normal are never displayed. This increases the recognisability of the Mesh and considerably speeds up drawing. With Slower/Faster Draw, you can specify that additional or fewer edges must be drawn when you are not in EditMode.
• Double Sided - Only for display in the 3DWindow; can be used to control whether double-sided faces are drawn. Turn this option OFF if the Object has a negative 'size' value (for example an X-flip).

• No V.Normal Flip - Because Blender normally renders double-sided, the direction of the normal (towards the front or the back) is automatically corrected during rendering. This option turns this automatic correction off, allowing "smooth" rendering with faces that have sharp angles (smaller than 100 degrees). Be sure the face normals are set consistently in the same direction (CtrlN in Edit Mode).

However, this can give the appearance of non-shadowed light somehow magically coming from within a confined space. Unless you tell it otherwise, CG Spot lights light up everything they touch going in a straight line from the light to the surface to the camera. They do not respect mesh faces or obstacles or whatever, they just go. If you turn on Ray or Buffer shadows, then when it hits a mesh it says, "do I keep going and/or cast a shadow" - if there is a material with an alpha (or no material assumes alpha 1), it gets halted and instead turns that light-ness into shadow-ness and continues on its way, but now casting a shadow instead.

The flipping normals is a trick to sorta go half-way between by making it think that the material is flipped and reflects light only when light is coming from the other direction. The images show a box with a side facing the camera removed, and the box is lit from behind by a shadow-less light. With No V.NormalFlip disabled, the inside faces of the box are "lit" by the backlight. In real life, the only way these faces could receive light is by ambient light. With No Flip turned on (enabled), these side faces' normals face outward, and thus the insides do not reflect any light, providing a more accurate representation without having to enable shadows.