I like to know can we make a web site or application(or using something free like google map) to routing a way and our robot can follow the line exactly? For example I like to build a quad-copter and specify some streets on the map and my quad-copter flies upon that specified streets.
In order to implement the line following function you need to make several design choices which will affect your robot performance and accuracy.
Here are some examples:
GPS Coordinates: using a GPS receiver the robot can navigate through a set of waypoints represented as coordinates (or elevated coordinates for an UAV) to follow;
Compass Heading: using a calibrated compass can lead the vehicle on a certain path with a given set of headings;
Inertial Navigation: using a IMU and EKF the robot can estimate its position knowing the starting point, however the accuracy will be highly dependent on the quality of the sensors (commercial grade IMUs are not suitable for precise odometry).
To set up waypoints on the run you can use either a radio, a web (socket, HTTPSync, REST, ...) or satellite link. There's lots of choices for the GUI too, ranging from a native app to a web interface or a traditional software.
To recap, if you can specify the sensors you would like to use and the communication channel I can expand on that.