Radar

Summary
Radar is Apple's internal bug reporting and tracking system. URL's used in it are of the form "rdar://problem/123456". The Radar app seen on iOS is a web application. Start Safari, navigate to "rdar://" (without quotes), then hit the bookmark button and "Add to Home Screen". Wait a few seconds for the favicon to appear in Springboard and rename the title/web app name to "Radar".