The vertical gardens have been used recently in some new buildings in different countries and sometimes on the roof too!
This technique is use by Arquitects to bring more beauty to the place and a extra clean air to the over crowded cities.
The restaurant Bon Restaurant Paris 20è in Paris (pic) got it and is really pleasent, The shop Replay in Barcelona is another example presenting their products with the garden.
Another common use it the eco urban farms, as the use of the resource is by far much better and the productions is higher (-space, +production).
Singapore has the vertical lunch project, a new super-efficient vertical farming system producing greens for the 5 million residents of the crowded city-state. The reason is to produce their local products, reduce the cost and the impact on the economy and ecosystem.
At home it is pretty easy to have one even recycling plastic bottles and using it for aromatic herbs or those to add to the main dish as oregano and similar plants.
This video will give you some ideas http://www.youtube.com/watch?v=K9vN2eudWcQ
Both reasons are equally a good option to apply in your place.