A few days ago I put together a wicking worm bed. There's plenty of information available on wicking beds and wicking worm beds on the www (links below). The main advantage of a wicking bed is that it's a low water use garden bed compared to traditional overhead watered garden beds. In a wicking bed the water is contained beneath the soil in which vegetables are grown and is "wicked"up to water the roots. This is a far more efficient way of watering especially in the dry areas of Australia and other parts of the world.
The beds themselves involve quite a degree of effort to set up. We bought the frame, internal plastic liner, length of agricultural pipe, geo-textile layer and plastic outlet as a kit from 2 Acre Woods but you can build them from scratch with materials obtainable from many hardware stores. Either way you'll also need a quantity of gravel or sand through which the ag pipe runs and where the water is contained. Then you'll need good quality soil or compost on top of that. So there's quite a bit of reasonably heavy physical work.
Once I set up the frames I lined them with the sheet of plastic (or pond liner). You have to be careful not to puncture this! I used large bulldog clips to hold the plastic in place on the frames (they can be removed when the soil has been put in the bed). Then I carefully made a small hole in the plastic in line with the pre-drilled outlet hole and fitted the outlet pipe (pictured above). The ag pipe (slotted pipe) is placed across the plastic from near this outlet to the other side of the bed and stretches up to the top of the frame (this is where the water is put in). I've seen some variations where a length of solid pvc piping is used to deliver water to the ag pipe in the bottom of the bed.
Gravel is then carefully placed around the ag pipe to just cover it. Water the gravel to check for any unevenness and to make sure the overflow pipe actually overflows then cover the gravel with geo-textile (this stops the soil, which is placed above the geo-textile, dropping into the water below).
A variation for wicking beds is to include a worm farm to increase the fertility and texture of the growing medium. I used a quantity of compost to supplement the soil that I put in my wicking bed and the compost has a number of compost worms in it so I added a "worm farm" by using a largish plastic pot with an oversized plastic dish as a lid. I've also used a small pot to cover the top of the ag pipe that is sticking out the top of the bed so that extraneous material doesn't fall into the water below.
Wicking beds can be constructed in small containers, such as polystyrene boxes, or in large garden situations. To find out more about wicking beds and wicking worm beds have a look at:
2 Acre Woods (Adelaide Hills)
Scarecrow's Garden (Mid North South Australia)
Maireid Sullivan (Victoria - comprehensive e-book available)
Waterright (extensive information from Colin Austin, the developer of the wicking bed system)
Wicking Beds - The Way To Health (Colin Austin's personal site)