I have replaced about a quarter of the light bulbs in the Oz
Report World Headquarters with LED lights like these:
http://ledtrailerlights.com/rv/RV-1141.htm. At a little under $16, they cost
10 times the cost of a regular 12 volt incandescent light bulb that fits in the
same socket. But I like these bulbs, not only because they last much longer
(25,000 hours), so that they pay for themselves (if I was actually paying
specifically for the electricity, which at RV Parks one usually does not do
unless you stay for a long period and they have individual meters), but also
because they are cool to the touch. I no longer have little furnaces putting out
more heat than light. This reduces stress on the fixtures, the circuits, and the
circuit breakers.

I have not replaced all my many lights in the trailer (40 or 50, amazingly
enough) with these bulbs because most of the lights are very rarely on. I'm just
replacing the light bulbs that are often used.

LED's are getting better and cheaper all the time with improvements in the
technology. You can see an example
here.