Below is a zoomed in view of the area around the Pariser Platz and Brandenburg Gate.
The web site also has aerial views, history, photos and tourist information.
There is also a 3D view although it requires the Google Earth plugin and does not allow for much interaction.
Here is an aerial view of the Checkpoint Charlie area combined with a map of that location.
The City has also constructed a hiking and bicycling trail along the 160 kilometers of the former border, most of it following the border control roads used by the two governments. The website has a nice description of each section of the trail and also has a link to the Mauer Guide, a downloadable GPS tour that traces the path of the wall with historical information. The guide can be loaded to a cell phone or other handheld device.
Happy 20 jahre mauerfall!