LED's have come a long way in the past few years and they look like something that would be perfect for growing plants because...
1) They put out VERY little heat
2) They can put out ALOT of light
3) They are cheap and last forever
4) They are very small
What I don't know about them is if they have been proven as grow lights. Has anyone here used them for plants? I have an LED desk light that easily puts out more light than my twin 30w CF terrarium setup and it only has 3 LED's.