I received an interesting email about a new product, The Garden Tower. It combines growing with composting and growing plants vertically. I've watched their video and was impressed. The Garden Tower uses about 7 cubic feet of potting soil and looks suited to urban gardening where space is short. Here is their information:

Garden Tower Project is a socially responsible company located in Bloomington, Indiana. Our mission is to help change the way our world grows its food. Visit our brand-new website www.gardentowerproject.com.
You can follow our progress on facebook at Garden Tower Project and read our daily Garden Haiku on twitter @gardentowerproj. I also have a blog at http://gardentowerproject.wordpress.com/ in which I ruminate on matters vegetative and provide updates on our various Tower experiments."

I'll be following this company to see what happens, as it looks like has potential for city gardeners.