Vdara hotel Death Ray. Basically, a curved shiny building makes a hot spot. You have to read the story, but how about some back-of-the-envelope calculations? In particular, would this building be able to melt some plastic bags and stuff?
From the pages of MAKE:
Made on Earth. MAKE 03 – page 16. Reports from the world of backyard technology, including a shopping cart go-kart, the “Solar Death Ray,” a demolished house sculpture, a gas tank bass instrument, and some seriously big speakers.