What is claimed is:1. A method comprising controlling, at least in part in accordance with a chaotic function, an artificial light fixture to produce light for general illumination within a space,wherein the chaotic function comprises a mathematical expression that determines a variation of the artificial light in a dynamic manner that appears random to a person in the space generally illuminated by the artificial light, andwherein the mathematical expression is dynamic and highly sensitive to an initial condition.2. The method of claim 1, further comprising limiting the extent of variation of the artificial light to less than or equal to a predetermined maximum amount.3. The method of claim 1, further comprising limiting the rate of variation of the artificial light to less than or equal to a predetermined maximum rate.4. The method of claim 1, further comprising controlling the artificial light at least in part in accordance with a combination of a nominal function and the chaotic function.5. The method of claim 4, wherein the combination of the nominal function and the chaotic function approximates a natural variation of light.6. The method of claim 4, wherein the nominal function is a set level for the artificial light.7. The method of claim 4, wherein the nominal function comprises a combination of a set level for the artificial light and a variable function.8. The method of claim 1, further comprising controlling the artificial light at least in part in accordance with the chaotic function in a state that is unstable with attractors.9. A lighting system, comprising:first and second lighting devices each comprising a controllable source of artificial light; andat least one controller coupled to control an operation of the sources to produce artificial light for general illumination within a space,wherein the at least one controller is configured to control artificial light outputs of the sources at least in part in accordance with a chaotic function,wherein the chaotic function comprises a mathematical expression that determines variation of the artificial light in a dynamic manner that appears random to a person in the space generally illuminated by the artificial light, andwherein the mathematical expression is dynamic and highly sensitive to an initial condition.10. The lighting system of claim 9, wherein the artificial light outputs of the sources of both the first and second lighting devices are controlled at least in part in accordance with the same chaotic function.11. The lighting system of claim 10, wherein the artificial light outputs of the sources of the first and second lighting devices are controlled at least in part based on the same chaotic function in an in-phase manner relative to each other.12. The lighting system of claim 10, wherein the artificial light outputs of the sources of the first and second lighting devices are controlled at least in part based on the same chaotic function in an out-of-phase manner relative to each other.13. The lighting system of claim 9, further comprising:a network, wherein:the at least one controller comprises a first controller in the first lighting device coupled to control the controllable source of artificial light in the first lighting device and a second controller in the second lighting device coupled to control the controllable source of artificial light in the second lighting device;each of the lighting devices further comprises a communication interface configured to enable communication of the respective first or second controller via the network; andthe communications via the network facilitate the control operations of the sources in the first and second lighting devices to vary the artificial light outputs at least in part in accordance with the chaotic function.14. The lighting system of claim 9, wherein the at least one controller is further configured to limit the extent of variation of each artificial light output to less than or equal to a predetermined maximum amount.15. The lighting system of claim 9, wherein the at least one controller is further configured to limit the rate of variation of each artificial light output to less than or equal to a predetermined maximum rate.16. The lighting system of claim 9, wherein the at least one controller is configured to control operation of the sources of the first and second lighting devices so that the artificial light outputs vary at least in part in accordance with a combination of a nominal function and the chaotic function.17. The lighting system of claim 16, wherein the combination of the nominal function and the chaotic function approximates a natural variation of light.18. The lighting system of claim 16, wherein the nominal function is a set level for the artificial light.19. The lighting system of claim 16, wherein the nominal function comprises a combination of a set level for the artificial light and a variable function.20. The lighting system of claim 9, wherein the at least one controller is further configured to control operation of the sources of artificial light of the first and second lighting devices so that the artificial light outputs vary at least in part in accordance with the chaotic function in a state that is unstable with attractors.21. A lighting device, comprising:a controllable source of artificial light; anda controller coupled to the source of artificial light, wherein the controller is configured to control an operation of the source to produce artificial light for general illumination within a space at least in part in accordance with a chaotic function,wherein the chaotic function comprises a mathematical expression that determines variation of the produced artificial light in a dynamic manner that appears random to a person in the space generally illuminated by the produced artificial light, andwherein the mathematical expression is dynamic and highly sensitive to an initial condition.22. The lighting device of claim 21, wherein the controller is further configured to limit the extent of variation of the produced artificial light to less than or equal to a predetermined maximum amount.23. The lighting device of claim 21, wherein the controller is further configured to limit the rate of variation of the produced artificial light to less than or equal to a predetermined maximum rate.24. The lighting device of claim 21, wherein the controller is configured to control the operation of the source to produce artificial light at least in part in accordance with a combination of a nominal function and the chaotic function.25. The lighting device of claim 24, wherein the combination of the nominal function and the chaotic function approximates a natural variation of the light.26. The lighting device of claim 24, wherein the nominal function is a set level for the produced artificial light.27. The lighting device of claim 24, wherein the nominal function comprises a combination of a set level for the produced artificial light and a variable function.28. The lighting device of claim 21, wherein the controller is further configured to control the operation of the source to produce artificial light so that the produced artificial light varies at least in part in accordance with the chaotic function in a state that is unstable with attractors.