How do you hang stuff—from the walls or ceilings—around your house when you're decorating?

It took me a while to find a good, non-destructive way to put up posters in my living room. I think I started with blu-tack, which dried in a few months and the posters came down. Then I tried 3M's hanging strips, which stayed on the wall for longer, but was pretty expensive for what it was. A year ago I had the idea of using velcro that has adhesive tape on the other side. So far this has worked near perfectly for me.

I know I'm not breaking new ground here, but I was happy to finally find a decent solution. Well, at least for light objects on walls (and elsewhere).