Extension Methods

Extension methods extend functionality of existing types.

EditorGUIExtension - Some extensions to make coding the GUI for utilities/custom inspectors easier.
Enum.TryParse - Provides an instance TryParse method for enumerations.
GenericMenuExtensions - Allows you to cleanly add items to GenericMenu instances using chained method calls.
GetOrAddComponent - Simple extension to save 2 or 3 lines of very redundant and ugly code.
IsVisibleFrom - For checking if a Renderer is rendered by a specific Camera.
LayerMaskExtensions - For manipulating and debugging LayerMasks.
QuaternionExtensions - Provides a few useful extensions to the 'Quaternion' struct.
TextureFloodFill - Two methods for Texture2D which allows you to perform a floodfill operation on the texture.