Most of you may already know about how kewl Google Maps is, but for those of you who don't you should check it out. Google Maps has a very slick interactive interface, coupled with a powerful mapping system on the backend. This combination makes Google Maps a winner in my book. The mapping software allows you to search for local hangouts, landmarks, and businesses, and then plots them on an interactive map. So far the only challenger has been Map24, an international system that uses an attractive Java applet, and which takes much longer to load.
Google has recently added satellite imagery to the mapping experience. You can search for famous landmarks and in most cases get a detailed satellite image of the location, all for free. Some areas are not yet mapped out and the detail limited, but it is still kewl to see your house or local diner from space ;)
Recently people have been hacking the mapping feature. myGmaps enables you to create, save and host custom data files and display them with Google Maps. You can read about it, and create your own customized maps here.
So visit Google Maps, and play around. I am sure once you do you will never go back to mapquest ;)