“ Earth Hour 2009 is set to switch off the globe. Already 538 cities in 75 countries which is double the number of countries that participated in 2008, are committed. With hundreds more cities expected to sign up to switch off in the coming months, Earth Hour 2009 is setting the platform for an unprecedented global mandate for action on climate change. ”

Earth Hour

I think they got the idea from Bali where every year all lights are switched off and no cars or motorbikes are running for 24 hours in occasion of the balinese new year's day (Nyepi) which usually is celebrated in March.

“ Watermarks is a public art project that will use a series of large-scale projections at sites across the centre of the city to explore these questions. Flood level marks will be projected on to the sides of buildings, showing how high water levels could potentially rise as the sea inundates the central, low lying areas of Bristol. By displaying these levels in real space, the project aims to help us to imagine the depth and extent of this potential future flooding - allowing us to measure them against ourselves in familiar environments. ”

The Watermarks Project

A good idea, usually visual reminders are better eye openers then just words.