I built something like this many moons ago for browser history. A service would run on your machine to aggregate your browser history. Typing "http://" anywhere on your machine would pop up a dialog with your history of most recently visited sites. I wonder if browsers have gotten better with APIs for web history and if it's any easier in windows. System-wide keystrokes had to be checked with win32 calls which could set off antivirus alarms. Keep up the good work. Maybe this will inspire me to see if things have gotten better.