EnumFlags

Privides a dropdown interface for setting enum flags:

public enum Direction
{
    None = 0,
    Right = 1 << 0,
    Left = 1 << 1,
    Up = 1 << 2,
    Down = 1 << 3
}

public class NaughtyComponent : MonoBehaviour
{
    [EnumFlags]
    public Direction flags;
}