Use your cellphone light underneath a water bottle to make a lantern that distributes light better than the direct beam. Coloured liquids make the light look cool.
As a side note this reminded me of an article about low cost housing in the Philippines, that they use clear bottles filled with bleach and water anchored in the ceiling to provide light within the homes. The plastic water bottles provide free light with an output of about 55W. It takes five minutes to make, and using a hammer, rivet, metal sheets, sandpaper and epoxy, it costs $1 to produce.
Stuff required to make this work:
1 – Cellphone with camera light
1 – Coloured bottle of water
I give this device an overall score of 2/5