Crayon heart wall art - arrange in a heart and melt crayons with a blow dryer. add a picture in the middle to use it as a frame. Okay I've seen the crayon melty thing before but I love the heart/picture frame idea!
Easy Art For Kids - Experimenting with Water Colours
Glue crayons to a piece of cardboard or to the a canvas. Then get a blow dryer, turn it on, and hold at an angle. The crayon will start to melt and drip in the direction of the hot air. Put cardboard behind the art piece, the crayon will splatter.