UnrealEd Advanced Options

Holds the advanced properties for UnrealEd, and also many that affect the game itself. To open this from the Editor do:

Of interest to mappers is the "Editor" group of properties.

This allows funky stuff like strange grid settings and other weird options...

Properties

AlwaysShowTerrain: ?
AutoSave: see below
EditPackages: array showing what's loaded ... no idea if messing with this is a) dangerous or b) has any effect
FovAngleDegrees: ?
GameCommandLine: "log"
GodMode
LoadEntirePackageWhenSaving
ShowIntWarnings: ?
UseActorRotationGizmo: The UDN Getting Started Table of Contents page briefly mentions a "RotationGizmo", describing it as "the new selection-manipulation tool that comes with the UDN build".
UseAxisIndicator: controls appearance of those little x-y-z axes in the UnrealEd Viewports.
UseSizingBox: ?

I know a lot of people you have lost a lot of work because of an editor-crash and they didn't save their map.

Global brush colours can be set somewhere around here too.

It's perfectly possible to:

Set the grid to a number that isn't a power of 2, though inadvisable as powers of 2 are optimal for clean BSP.
Set the grid to different sizes in different axes, eg 16x16 in top view, and 64 along the z-axis.
Set the grid to fractional sizes, eg 0.5.

The rotational grid makes rotating objects in the interface rotate in discreet increments.

RotGridEnabled: Whether the rotational grid is active or not – you can set this in the Console bar too.
RotGridSize: the settings for the grid. The grid is set separately for the pitch, roll and yaw. The default value is 1024 unreal units, which is 64 steps per circle, each of 5.625 degrees. You can use any number, though powers of 2 are best (just like the linear grid); see unreal unit for suggestions.