Eco gadgets - have some to share?

I have one interesting tip in the topic like this that combines gardening and ecology – it is a self watering flower pot made of old plastic bottle. How to make something like this you can find here: http://www.liveoutside.co.uk/134-self-watering-flowerpot.html

I haven’t tried it myself but it looks quite nice. And that’s why I have started wondering if you have something similar to share with oters?

All ideas well wecomed!
Alice