Google is now showing you maps of the Mars. This feels just like Google Maps for earth, or the previous Google Moon*. You can switch between three different map types; elevation, visible**, and infrared. A list of "links of interest" (like where spacecrafts landed), as well as named mountains, canyons, dunes and craters is also available.
Google in their Mars FAQ says they're working on a version of this Mars data to be used in Google Earth (desktop) clients.
*Google Moon was only a half-serious project though (try zooming in as close as you can to see why).
**As to why this visible map is in gray-scale, not color, Google replies: "In true color, Mars pretty much looks like butterscotch. We chose a gray-scale map in order to highlight more surface details."
Signs of a coming Google galaxy...
As the Googlist notes, Google Mars may only be the beginning of a coming "Google Galaxy." Back in 2005, Google registered the following domains for Saturn, Jupiter, Venus, Pluto and so on (always with .com, .org, .net and .info):