Lately I have been using ACME Mapper 2.0. It is a combination of 8 different servers. Half of the options come come directly from Google. The other options are varied and and interesting.
There is an option that provides topographic in varying resolutions.Below you can see Mono Lake as it looks on three different scaled maps. This map server zooms in on one map and then changes to a different map as zoom in and out. The setback for this map server is that there is not complete coverage everywhere in the world.
Here are images grabbed from topographic server at ACME Mapper 2.0 of Mono Lake in three different resolutions using three different maps.
DOQ is also available but it is limited to the US. It looks interesting from a technical point, the curve of the earth is adjusted to create flat images.
There is a feature to tie into weather data. It is part of a system called NEXRAD, it is another American funded system however there is some limited coverage into Canada. Here are two images of a storm system in Lake Ontario taken about 40 minutes apart.
|1:02 AM 6/19/2012|
|1:32 AM 6/19/2012|
Mapnik is an open source mapping program, as such it can be uneven. Take a look at this region in Silicon Valley near the intersection of the Union Pacific and the Bay Shore Freeway. This area has the buildings outlines and driveways marked. Nearby neighbourhoods are not so extensively mapped.
Mapnik also allows for mapping of pedestrian pathways. Look at this image of downtown Toronto where the sidewalks, pavement in a park and underground passageways are all marked.