Just sharing these:
Google maps at http://maps.google.com
Wikimapia at http://www.wikimapia.org/ which also has links added by the community to useful things such as schools, pubs, shops etc. Not to mention useful information like how close Parafield airport is to Mawson Lakes...
We used google maps when looking at a really lovely place in Wellington NZ and discovered that it was within cooee of a quarry! You don't find that sort of information on a real estate agent's listing.