I’m not sure if this is what you are looking for but if you have a GPS or want one with you map software this is great.
http://www.macgpspro.com/
I realize now you may have meant road maps for driving. If that is the case and not for TOPO Maps try this.
http://www.routebuddy.com/
I do not need it for GPS. I work for a transportation company and need to calculate miles for trips that we do for people. I need somethings similar to Microsoft Streets and Trips.
Well, i use Google Maps for this purpose and i’m very much satisfied.