My fish tank, which I admit is BIG user of energy, is a significant example.I'm currently running an LED set that runs at 320w when fully powered up and all three light banks are running. An equivilent Halide/VHO setup would be anywhere from 750w to 1kw for the same output. That's no joke right there.
I recently converted my pinball machine over to 100% LED's, which replaced about 100+ little #44 incandescent bulbs. It went from about 180watts down to about 75watts right now. With some other changes I'm making in more modern circuitry, I'm thinking I can get it down to perhaps 45w to 50w. Switching from NMOS to CMOS electronics, a more modern power supply, swapping plasma score displays for LED's..... there's a lot of room to play with still.
In both cases you also have to figure in the huge reductions in heat too.
Longevity, who knows what I'll actually see, but I do know that both of these things are absolutely brutal in their requirements to replace incandescent and flourescent lamps.