Open source or *BSD/Linux compatible mapping software?

[John]

Hey, folks - my one remaining dependency on the Microsoft world
seems to be Streets and Trips.  Even though the product has gone
down hill dramatically in the last three years, I still love it
and use it daily.  One of the big differentiators for me is that
it doesn't require an Internet connection to function - anywhere
I have my laptop, I can do mapping and even fix my position with
my GPS.

Is there anything like this available for us FreeBSD users?  It
doesn't have to be open source - I pay for S&T and I'm happy to
pay for its equivalent.

Thanks!
-- 

John Lind
john at starfire.MN.ORG