Open StreetMaps is a worldwide collaborative effort to create a high quality, unencumbered street-level map of the world. When I first came across it, a few years ago, Co. Galway was almost unpopulated (with mapping), and Galway city extended as far as Moneenageesha.
Things have changed, however.
On Marlow's suggestion, I downloaded a daily Garmin build of the Ireland map and installed it to SD card for use on my Nuvi.
One of the OSM contributors creates regular builds converted to Garmin .img format and makes them available for download from here.
Alternatively, a slightly less comprehensive (no Irish Language) map can be downladed from here.
Either way, the next step is to create a directory 'Garmin' on the root of an SD card. It doesn't need to be a big card, as the biggest Ireland map file is about 75MB.
Copy the .img file (after unzipping, if necessary) to the Garmin directory, insert into a compatible Garmin GPS and power on. After a few minutes it will start up. Press 'Settings' -> 'Maps' -> 'Map Info' and uncheck all but
the OSM map you wish to display. Go back to the main menu and select View Map to see your newly installed map.
From what I have seen, the current state of OSM is vastly more up to date, and much more detailed than the Navteq offerings from Garmin. And they're free (as in speech/beer).
If you wish to build your own maps, current OSM map extracts may be downloaded here. These extracts can be converted to Garmin format using mkgmap. You may use standard styles, or create your own, so if the standard colouring grates with you, you can create maps with the orange background, and pink roads you have always craved.
Visit http://www.openstreetmap.org/ to learn more and maybe contribute yourself!
