If you want something easy, that works straight after installation, then move along, nothing to see here... However...

If you want turn by turn with voice, support for Garmin maps, OSM, and maybe others, the ability to do route calculation off line, POI's, bookmarks, and on and on, then take a look at Navit.

Latest armel build is 3684 (17 November 2010) which works well for me. You'll need to hunt around to find working XML config files, or spend a few hours tweaking the defaults to your liking.

You can find it here