Aquaponics is like hydroponics, but without the chemicals.  You keep fish in a tank, and they feed the plants with fertilizer.  The plants filter the water keeping the fish in an optimum environment. Initially such a system is a bit expensive, especially in the form of the red/blue LED lightbulbs like the ones used in the Farm Fountain.  They are growing lettuces, herbs and other small veggies like radishes, all year round.  I'm particularly interested in growing edible tilapia fish.

Edit: HEY!  This is post 100!