Science Applications International Corporation
Selling computers, software, and services to individuals or even companies can be something of a chore, because people and companies eventually run out of money with which to buy even the most coveted stuff. But over the last ten years, the various U.S. defense, law enforcement, and intelligence agencies have proved themselves eager to spend on high tech -- which explains Science Applications International Corporation's $10 billion in 2009 revenues, as those organizations are its primary clients.
SAIC has made plenty of money on perfectly normal projects, like modernizing various Army systems. But then there are the weird ones, like the Stargate Project, which sought to harness psychic phenomena for military purposes. Or the mysterious ones, like the Trailblazer Project, a vast NSA data-mining operation that was eventually killed after a number of whistleblowers revealed dubious spending and purposes. Or just plain failed ones, like the Virtual Case File program for the FBI that cost $170 million and was abandoned unfinished.