A Giant Network of Trampolines Suspended in an Abandoned Welsh Slate Mine Open to the public July 4th, 2014
Trashswag is a crowdsourced map for people to share and post reusable materials that they spot left outside. It is a resource for creative hobbyists, artists and people conducting renovation works to find unique, salvageable old wood, windows, doors, metal, glass and furniture. So far I think it's mostly Toronto and Montreal but is expanding to other areas.
Bootleg Objects, the site of two artists in Germany, have done some really amazing work retrofitting popular technology to serve a new and/or unintended purpose -- just because they can. It's quite beautiful design -- who knows of other examples?