For most of us, it's remarkable enough to access the Internet from a plane 10,000 meters in the air. But when Swedish process-control engineer Ulf Olsson does that -- as he did recently while flying over Arizona -- he's also monitoring an iron-ore drill 1,000 meters below the earth's surface in northern Sweden, thanks to underground Wi-Fi.

While cities like Philadelphia wait for citywide Wi-Fi networks to come on line, the world's iron, coal, and copper mines are getting fat wireless broadband pipes. By early next year, the mine in Kiruna, Sweden -- 150 kilometers north of the Arctic Circle -- will complete its installation of Wi-Fi-linked drills. A German mining company, Deutsche Steinkohle, is installing several hundred Wi-Fi hot spots in its coal mines. So is a copper mine in Chile called El Teniente, which claims to be the world's largest.