The permaculture idea of using every darn inch of your property to grow stuff appeals to me. Plus I like green stuff on my walls, so these hanging planters look a good idea.
Picked these up at a garden centre: sturdy re-usable ripstop pouches with a bunch of holes in. Kinda like a hanging grow-bag or low-profile hanging basket - ideal for my tiny garden as I don't have space for either, but I do have some scraps of wall that aren't earning their keep. Work, you lollygagging slabs of vertical masonry, work! *
whipcrack*
They're stuffed with compost and some water-retaining gel. I've got late-season strawberries in one, and a hanging-basket variety of cherry tomato in the other. If these work out, I'll get a bunch more and make a hanging salad wall.