We have a Garmin Nuvi for my wife's Volvo that does not have navigation. Very good unit though our's is several years old now and no longer made. Check out there website...
I've also heard good things about TomTom but have no personal experience with their products.
Current: 2011 Space Grey E90 M3, DCT, Comp. Pkg., Conv. Pkg., everything but Cold Weather Pkg!
Gone: 2008 550, Space Grey, Sports Package, Sport Auto Transmission.
Sold: 2004 545i (U.S.), Steptronic, Silver Gray.