Scott actually did this the day after we dug the garden, but I've been slacking at taking the photo and posting it!
We bought a 10' strip of gutter and a downspout at Lowe's and Scott cut and hung it. When the water comes off of the roof, it goes down the downspout and into the barrel. The barrel has a mesh hole in the top to keep out debris. The spout at the bottom uses the pressure from the weight of the water to power fill the hose... and water our plants!