I like it when I get one on the page of my book travelling in to work on the tube. The light gets refracted through the edge of the glass partition in the carriage, and if it hits it right, it projects a straight spectrum onto my page. I sit there and smile at it. Once I got asked what I was smiling at, by some grumpy bugger who thought I was laughing at him. I told him about the rainbow and he came over and sat next to me to see.. He was OK after that....

LTS