You can do straight line distances.
I use it on my daily walks to calculate routes.

Try google-pedometer <http://www.gmap-pedometer.com/> .

Yes, I call it "a ruler"... Just kidding. But seriously, were you looking
for Outside, real-world distances, or or trying to measure point-to-point
distances from within something like a CAD program or an image file?

I am a ham radio op. I am looking for a database program which will tell me
how far away the station I am talking to is from my position.

If you have the address how about Google maps?