It’s no secret that even GPS units are subject to GIGO (Garbage In, Garbage Out), leading users astray due to incorrect map data..  People have even been led to the edge of cliffs.  Wouldn’t it be appropriate to hear the expression “D’oh!” if such a failure occurred?Well, you won’t, but you can get directions via Homer Simpson, at least if you use TomTom navigation units.  TomTom users can go to www.tomtom.com/simpsons and download the voice for $12.95 or €9.95.  Sorry, it’s not