Random PCB based USB lights from China.

These are little PCBs that plug directly into a USB power source either way round, and light up. One type is just a plain light, another is a dark sensing night light and the most complicated has a touch sensor that dims the light in or out.
All the PCBs are about 0.1" thick (2.54mm) and just under half an inch wide (about 12mm). They have gold plated connector fingers on both sides so they can be plugged in either way up, and to prevent the +5V rail from shorting to the screened metal socket they have diodes on both the positive connections.
These little things are neat. They only cost about a dollar/euro/pound or two each including shipping and are available in cold or warm white.
Yes I am drinking diet Pepsi with absinthe in it. Super-aromatic.