I just came across this site after watching the presentation on TED. From what I’ve seen, this place and the ideas here are fantastic.
I wanted to share a system I build and have been using successfully. Having seen the systems on this site, mine looks huge and clunky!
I live in Las Vegas, Nevada, which as most know, is very hot and dry throughout 9 months of the year. I have a small yard, but no usable soil for growing a garden. I don’t know much about gardening, but its something I’ve wanted to try. My goal is to have a year round system that I can use to produce herbs, lettuce and other greens.
My system is a free standing, recirculating pump based system. It has a reservoir full of nutrient solution that gets pumped up to a system of PVC pipes. The water flows through the top pipe and then down to then lower pipe, and so on, until draining back into the reservoir.
Each pipe contains four grow sites, spaced about a foot apart. Each grow site has a net pot filled with clay pellets.

My Hydroponic System
Before planting, I had started some beans, lettuce, tomatos, green onions and peas inside in a growth medium that I could easily transfer to the netpots. You can see these small starts already planted in the photo above. Below is a photo taken several weeks later. I had since put a “green closet” (small green house) around the structure to help control temperature and filter out some of the intense sun. The green house is made out of PVC pipe, made rigid with wood bracing and covered in 7 mil painters plastic. In the photo below, you can see that the tomato plants are taking off, peas are doing ok and the onions and lettuce are still slow to get going.

Progress!
All of my starts did not take off. My beans did not survive at all, and all but one lettuce plant died. I attribute this to planting too soon, before the starts had developed good roots.
Here’s a shot of the root system for one of the tomato plants:

Tomato Plant Roots
These roots actually started to become an issue. They started to grow so much that they would block the pipes and cause water to back up in the system. A little bit of a “hair cut” fixed that (for a little while…)

It's a jungle in there!
The above photo was taken just a week ago. The tomato plants by far had grown the most. So much, that I had to remove a few plants do to their roots blocking up the pipes, and to allow for the other plants to get more light. I have since added string support for the plants to cling on to.
We’ve been using the green onions and lettuce to make salads for 6 (two adults and 4 kids) several nights now. Below is photo of one of those plants, which we’ve been cutting leaves off of for a while. They just keep growing back…

Lettuce
Below is shot that shows how dense the roots get on the tomato plants. This is a pot I removed to thin out the garden.

Dense roots!
All in all its been a good experiment, and I can’t wait to build my next system, refining my ideas. Hopefully the information on this site and its users can help me out.
Pete