Create tunnels that allow you to go across the map. (i.e. when you go into a tunnel at the right side of map, you come out of the left side of the map) Could even make this so that tunnels can move you anywhere on the map.
Ghosts and Pacman should both be allowed to use tunnels.
Create a map data structure, which can be serializable, so it can be saved to file. Also create a map editor so that maps can be easily edited. Finally, refactor code base to implement map data instead of reading from hard-coded arrays.