I've been using Google Maps for my mapping software almost exclusively lately.  Although it isn't all that accurate (just last night I ended up several miles from where I needed to be), it's smarter and has a much nicer user interface.  Oh yeah, and there are no stupid ads. 

It's smarter because of how it handles what I type in.  Here's a little comparison:

Mapping site	State road	County road
Yahoo	US Highway xxx	County Road xxx
Mapquest	US Highway xxx	County Road xxx
Google	anything	anything

For example, if I search for "435 Route 206, Newton, NJ" on Yahoo Maps or Mapquest, it gives me an error.  It doesn't even give me a suggestion.  When I search for the same thing on Google Maps, it finds exactly what I'm looking for, no questions asked.  Google sees two numbers and knows you mean #x on street #y.  That's smart. #technology