I just found this rather interesting article about Aquaponics. Basically using water from your tank to water your plants, which some of you do when you do your PWCs. These people took it a step further though, made it all automated.
The article is here:
GenGreen Life » Aquaponics? It’s Farming for the Fishes.
The actual setup is on this site:
Farm Fountain - a sculptural ecosystem you can eat
They have some cool videos showing how it all works. Figured it would be worth the click for some of you addicts, like myself.