I still come across the little clip-on ones at flea markets.
It's worth noting that when these were in common use, the tree was usually no more than 3' tall. It was brought in from the cold and decorated on Christmas eve, so it was still relatively fresh, lit on Christmas morning, and never lit again. Usually the tree was taken down that night or at least the next day. So it seldom posed the threat that trees did later when they were larger and started being left out longer.
Maybe someone will come out with affordable flickering LED Christmas tree "candles," so we can have the effect without the danger.
What do you think?
What do you have?