Ok, I know HIDs (MH, HPS) and VHO CFLs are plenty to grow usually in terrariums or otherwise. However I have been reading about the possible future of LEDs in plant lighting.
LEDs (Light Emitting Diodes) are the little red(usually) light you see for power on most electronics. The solid plastic kinda bead lookin thing that lights up.
From what I understand LEDs also come in many, many nanometers of the spectrum. (I am not real good with the whole light spectrum technicalities). The idea is that by using say 600 LEDs in say 12 different ranges you have a light source whose light is only the useful ranges to plants. (Blue, red, white, etc...) Now that you have cut out unnecessary spectrum you also cut down on wasted wattage (watts=$$$ spent). Though as I have read all this is still being tested on different plants and as of now, it is suggested to supplement with a wide spectrum fluorescent. Do a google search for LED technology. Interesting none the less!