Based on my stats here on About Organic Gardening, I'm not the only one who is (just a little) obsessed/in love with the idea of gardening in raised beds. Aside from practicality, ease of use, and all of that other good stuff, the great thing about constructing raised beds is that you can really tailor your beds to suit your garden's style. If you have a more rustic garden, you might want to construct your beds from large rocks found around your property. I've seen beds that looked like they were surrounded by teeny picket fences, beds contained by wattle fencing...if you can build with it, you can make a raised bed out of it!
Here in my neck of the woods, the Lafayette Greens community garden, sited right in downtown Detroit, has some of the coolest raised beds, cust0m-built from steel to reflect the city's industrial history. The garden actually won an ASLA design honor award in 2012, and these beds are definitely a defining feature of the garden. (You can check out a slideshow of the garden, including several photos of the raised beds, at the ASLA website.)
If you'd like to make your own sheet metal raised bed, my friend and fellow garden writer Dave over at Growing the Home Garden posted a really helpful video in which he demonstrates building a raised bed made from metal roofing and lumber. I love the way it looks! If only I had room for one more raised bed...
What are your favorite raised bed building materials?