Relatively easy to keep due to advancements in technologies, they can even be built to recycle greywater (the stuff that goes down your sink). Putting these together can be difficult without the proper knowledge of anchoring, irrigation, and plant selection, but there are experts out there.
For commercial installations, Patrick Blanc (the creator of Vertical Gardens or le mur vegetal, meaning vegetal wall) is probably the most famous, covering Museums, Malls, Restaurants and more. There are a few others that offer DIY kits that you can order, such as ELT, who also produce green roofs much the same way.
These make great outdoor wall coverings, but some people even have them indoors, as living wallpaper. They can even be seen in stores as part of product displays or framed much like a painting. An added benefit is that it will increase humidity in the room (not to mention the smell of fresh air), for those dry climates. For a more technical description, check out the wiki article on green walls.
Just another way to reduce your carbon footprint, enjoy some fresh oxygen and surround yourself with a rainforest-like atmosphere.[via pingmag]