My Trimble SVee6-CM3s showed up today, I need to build the RS232 circuit yet.
On and off I've been toying with the idea of navigation. I just found BBBike
http://bbbike.sourceforge.net which appears to do autorouting with ESRI Shapefiles.
Further, with
GDAL and
Tiger/Line 2000 data one can construct Shapefiles for the U.S., at least, which should make this doable as long as you're willing to deal with problems in the data.
Sadly I don't think I'll have time for it this month but it looks like it might be hackable to be a spoken direction finder with the addition of Festival and some mechanism for selecting endpoints. Of course it may be that I hate myself for wanting to do anything with perl.