I would point you to Navit first, and then Roadmap. They are both still 'prebeta' if I understand things, but they are trying to do real navigation with turn by turn routing, using open source maps. They both seem awfully great to me, but I haven't installed them (since they are early versions they take some work to install if my reading is correct).

Again, if I understand correctly, Navit has more of a Europe and US focus, while Roadmap has a US focus. That may be due to the fact that US maps are open to the public, or due to the folks who develop them, but I distinctly heard some feelings that roadmap is really a US project for now (though their website indicates that they are trying to move beyond that) and that Navit is more on par with Europe and the USA. I think they both want to service *everyone* and it is only map access for free that keeps them holding to a geography.

Either way, they are open projects that will only get better, and they cost you only the effort to install them (unless you love them so much that you decide you can be a contributor!) Good luck, and if you find that one or either meets your needs, please post again to that effect (or if they don't meet your needs, I think that is a valuable post too)

Trying to add some useful links
http://wiki.navit-project.org/index....t_on_n770/n800
Roadmap: http://www.internettablettalk.com/fo...ad.php?t=17718
(If someone has better links, please post them, these may not be the most up to date.)