Google just launched a Maps Gallery: a centralised atlas of maps created by governments, non-profits and other organisations. Though it's still a nascent project, there's already a lot of interesting finds in there.
The maps in the gallery so far represent organisations like the World Bank, USGS, NASA, and the US Census Bureau—Google says it'll be adding more soon. (Click here for information if you want to get your organisation in on the fun). Probably the coolest part is that the maps are layered on top of the standard Google Maps UI so that in many cases zooming in gives you access to more details. Above is Earth at night, and below are a few of our other favourites from the first batch.