Updated November 29th, 2008 In the past we were the ones figuring out tricks to add topo maps to Garmin road units and that was limited to vector maps (see below for details), but Garmin surprised everyone yesterday when they published a method on their blog to import raster (i.e. pictures) maps into their latest handheld GPS receivers, the Colorado, Oregon and Dakota.
Amazingly enough, all it takes is a scanned paper map and...Google Earth, so it's likely some tool will quickly be available to convert existing Ozi maps (probably the most widespread format) to Garmin compatible maps. In the meantime you can use the Garmin's Guide for "Custom Raster Maps" of the "Handheld Portable GPS Receivers" to discuss and share tips.
Updated November 29th, 2008 - Forum member Boyd "does it again", after sharing a tip to navigate with topo maps on his SP2620 four years ago, he just found a way to add contour lines from topo maps to the standard City Navigator road maps used by the Garmin nüvi systems. This transparent layer can be easily toggled in the map settings. You can make your own contour maps by following the guide he posted in...
... this topic of the Garmin nüvi forums on GpsPasSion.
Posted October 7th, 2004 - It looks like October is going to be a "topo month", with new software releases, new articles and user feedback! Site member Boyd , shares with us in this thread of the Garmin forums how he was able to put the US topo maps to good use on his SP2620 while driving in areas where the Navteq coverage provided by CityNavigator just wasn't enough. This should also work on the recently released Quest. Of particular interest is the "trick" he points out that lets you combine CN's turn-by-turn route calculations with the detail rich maps of Topo USA. Details and pictures here.
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Updated November 29th, 2008 
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