Here's a fun, easy idea. My younger daughter got a glow in the dark solar system set for her birthday. We put a bunch of the stars on her ceiling, as instructed, but we had a bunch left over. The problem with glow in the dark items, in general, is that they never seem to get enough bright light to "charge" them sufficiently.
This was our solution to that problem: use a hot glue gun to attach the stars directly to the lamp shade. That way, they're very close to the bright light and get a good charge right before the lamp is switched off at bedtime.