I use LEDs in my spotted black snakes enclosure and they are great. Give off a very good amount of light and use next to no power. I did not bother with a power pack and have just wired it to a 12 volt battery with a switch to turn in on and off. Main advantage for this is that when using the battery only time you pay to run the light is when you have to charge the battery, and with how little they use you may only have to charge the battery once a year. The greatest thing especially with venomous snakes is that if you are working at night and you have a power outage you will still have this light running to see what the animals doing.
Cheers Cameron