gps navigation project?

[David Rysdam]

I've complained here before about how much I hate pretty much all GPS
devices/software. I finally partly-decided to half-heartedly make a
feeble stab at doing something about it!

There's 3 parts:

Maps: OSM is the obvious choice.

Routing: There's a bunch of good routers out there, although one major
thrust of my own thing involves changing the routing (or at least
exposing parameters nobody else seems to expose the way I want). I
figure I'll start with one of those with my own pre-processor in front
of it, then go from there.

Navigation: There doesn't seem to be a lot of work in this area,
although it's hard to google for without getting inundated by retail
product hits.

The debian repos have "navit" that does a full end-to-end thing, which I
don't want. I could maybe rip out just the navigation part, but their
Android app is so awful it gives me a bad code smell feeling.

Does anyone know of any projects that specifically target (and do a good
job on) taking a pile of maps and a GPX file and turning that into a
sequence of "in 20 miles, turn left"-type directions?