2007 has been a huge year for GPS technology. It has gone from a gadget that everyone knows about, but few have, to a gadget that everyone knows about and everyone must have. Very much reminiscent of the iPod making the mp3 player ubiquitous in every household. Here’s a listing of the top 15 bestselling GPS units, from dashboard units to portable fitness-related units, of 2007. The best part is all 15 units’ prices have been slashed unbelievably to clear out stock after Christmas with prices up to 75% off.