Mo(i)re for your money
I am fascinated by moire effects - whether they're unintended optical effects created by parallel grids or meshes, or beautifully considered like this piece in the Virgin book-in area at Heathrow airport. I love the way it moves as you walk past - turning like a propellor, and changing direction depending on your view-point.
I had a great write up by Bill Hamilton in the Wall Street Journal last weekend -
it made me feel very grand!