Remote-control devices use either light beams (line of sight) or radio waves (long-range). In boats, these enable you to place items in locations that would be difficult to wire. Light beams is restricted to line-of-sight. Radio control can be prone to external interference (and false activation).
Remote control of lighting allows you to turn on deck lights from a keychain control before you enter the cockpit or even from your berth. The door-lock systems for cars can be installed on a boat to turn a light circuit on and off.
Although used mostly in larger vessels, engine and instrumentation is being integrated into one electronic system. Mercury and MerCruiser is offering a control package for its engines.
Security alarms and navigation receivers such as GPS can all be integrated into one onboard computer or electronic device for display and control. Then you can use cell phone, PDA or computer to communicate with your integrated computer system from anywhere in the world. The techies reading this will say "cool, we can now run the whole boat from Timbuktu" - forget it!