Well, actually, just lights. Specifically, I am thinking about bike lights, and how far they have come in the past 30 years.
My first bike lights, in the late 1970s, were a set of bottle generators, with a headlight mounted on one, a tail light on the other. One of the generators mounted to the fork tube of my Triumph 10-speed, and the tail light generator mounted to the seat stay. They were both sensitive to the speed at which the tire turned the generator, so they got dimmer as you slowed down, and winked off completely when you stopped.
In the mid to late 80s, I had battery-powered headlight which was a diving flashlight equipped with a handlebar clamp. It ran off of 2 D-cells, and was quite a bit brighter than the generator light ever hoped to be. Still, the bulb was a 6-watt incandescent unit, and it was more of a "be seen by" light than a "see other things by" light.
In the 90s, halogen bulbs came on the scene, and rechargeable alkaline batteries appeared in bottle cages across the land. The lighting increased exponentially, but so did the cost.
Now, I have a light with LED bulbs and a Lithium-ion battery which runs for 17 hours, continuously, on low beam. It has a strong beam, and I thought it was just about perfect, until the first 24-hour race I used it in. Guys with lights only a year or two newer than mine would come up behind me, and I would cast such a shadow in the the beam of their lights that I couldn't see the trail (all while my light was still on!).
Five dollar LED flashlights, which run on 3 AAA batteries outshine even the best lights of the 1980s, now. It really makes me wish I could travel back in time to the times when we did a lot of off-road trail rides...