I had a pile of pressure-treated wood lying around that I got freecycle, and a stack of 1x12 pine boards left over from my parents house. So I built a multi-level planter with a built-in bench. I used pressure-treated for the bench, and the untreated pine for everything else. I figure the planter part will rot in a few years, but the bench should still be okay, so I'll probably just rebuild it at that point, especially if I end up getting an alaskan saw mill like I want to.
So far I've planted some potatoes, asparagus crowns, and flower seeds in this one. I'm going to round it up with some herbs when I get a chance.
Does anyone here have any interesting planter designs? I have a good bit more wood to use up.