A four solutions... Three don't require data.

1. Use an Android phone and/or tablet with OSM. OSM is an open source project to map every street in the world. You use the OSM data with an app. I use Osmand, but Locus Map also works. Both apps have fully functional free versions.

I use Osmand, it's got a Wikipedia layer, that is really handy. Routing and searches are not as good as Garmin, but the Wikipedia lookup is really cool and it's free.

2. Use downloaded Google Maps . You can now download up to 5 large chunks of maps with google maps. Maps have a lot of detail, but no routing or searching. It just shows you where you are on the map. Note: The download feature is NOT available in all countries. I know it works in Cuba, Mexico, India, US and most of Europe, but not in Thailand as of Feb, 2013.

3. Google Maps using data. This is really the preferred solution, since you get all the search and routing features that come with having access to data.

My take on it...
My preferred solution is data with Google Maps and OSM as backup incase of data issues. If data is expensive or unavailable then I use OSM with downloaded Google Maps to compare to. Not all map data is equal. Of the three sources, Google normally has the most data, but at times OSM or Garmin is more accurate. This can be city by city.

Anyway, I now leave the Garmin at home... The Android phone and tablet options are much more versatile and serve multiple functions when not playing navigator.