I was looking for something completely non-relevant to this site, when I came across the UK's National Maritime Museum. Specifically, the Charts and Maps section.

From their own description:
The National Maritime Museum collections contain more than 100,000 sea charts and maps dating from the medieval period to the present day. They document the results of exploration and discovery and show how techniques of navigation and surveying developed. Many were owned by naval officers and politicians and were used to plan and record the events which have become maritime history. The collections are not exclusively British and although they concentrate on charting the seas and coastlines, land maps are also included. Together they illustrate the work of the leading hydrographers and cartographers throughout the history of charting and mapmaking.
Just gorgeous...The only drawback is that some of the fancy on-line zoom things don't appear to work in firefox, though you can download most of the images....

-Rob A>