The other day I was looking to buy a GPS for my car when suddenly it occured to me that I'd love a Ghostbusters GPS. Just imagine it. The device could work like a PKE meter that makes the same beeps and crackles and has little wings which light up, rise and fall. The instructions could be voiced by Murray, Aykroyd, Ramis and Hudson and you can choose which voice you want to hear. The device could also have the siren from the Ecto 1 and when you arrive at your destination the theme song plays.
Mio Technology made one based on Knightrider a couple of years ago.
http://www.youtube.com/watch?v=IVEuYN4Q7_M
Perhaps we could contact one of these GPS manufacturers with the idea. I think that the actors would be willing to lend their voices, afterall they did for the videogame.