A cap for a container, having a light source contained within the cap, and a pair of conductors adapted to be in contact with a source of current exterior to the cap, the conductors being disposed so as to conduct current to illuminate the light source when they are in contact with the source of current exterior to the cap. The light source is desirably an LED. The cap fits a holder, which has means for detachably contacting the cap, desirably having spring action, and conductors providing a source of current to the pair of conductors in the cap when the cap is in contact with the holder.The holder desirably has multiple portions for use with at least a multiplicity of containers having such caps. The invention also includes a display rack, comprising means, e.g. LEDs, for directing light onto the top of each of a plurality of containers having a translucent cap.