If you are looking for LEDs for a project, now is the time to get them. The LED Christmas light have LEDs that you can use. I disassemble each light to get the LED out. Last year after Christmas I picked up a couple of strings for $2.00 a string.
The larger set had 5mm LEDs and the smaller one had 3mm. They don't have the lip around the bottom and most still have the anode leg longer. I did some testing and it took 6v to let the smoke out. I've been running 4 in series at 13.3v for a couple of days now. It takes about 3 volts to light one. If you hook up 4 in series, you can run that series in parallel with others to add more light.