Los Poblanos Organics - I've been to one of their gardening workshops before, and I always learn something new. In the spring, I'll use these as a seed-starting nursery, because we don't have enough space or bright enough light in the house to really get seedlings started well.
I've got some radishes and fava beans started in there, along with the kale I've been growing all summer, and some little starts of broccoli and Brussels sprouts. My big goal is to grow Brussels sprouts - possibly my favorite vegetable. I've tried them in the spring and they got full of aphids, so I wanted to try them in the fall when there are far fewer pests, but this has been an odd fall! It was so hot all the way through September, I couldn't even get seeds to germinate, then no frost until October 30, and just last week the overnight low suddenly dropped into the 20s and hasn't risen since. So maybe, just maybe, the hoop house will keep my little plants happy enough through the winter that they can burst forth in all their brassica glory as soon as it starts to warm up in the spring. I'm also planning to start some salad greens.
For each hoop house, I used 3 ten-foot lengths of 1/2-inch PVC Schedule 40 pipe. I stuck the ends into the ground just inside the frame of each raised bed, which is 3 feet by 6 feet. I bet you could do this without a raised bed, but you might need some stakes to tie them to. I covered each set of hoops with a 10 by 10-foot sheet of 4-mil plastic, which is available at Lowe's or Home Depot - it's much heavier than a painter's dropcloth, and it's usually near the building supplies - just ask them where to find it. Then I folded the ends in from each side and rolled them together and clipped them with clothespins. It's noticeably warmer inside there already!