The National Geographic Society has completely revamped their Education site, and it’s now in beta; lot of features and resources already there, with more being added on a regular basis. While there’s lots of information sources for browsing and downloading, maps are already a major focus (not surprisingly). There’s MapMaker Interactive, which lets you create and download thematic maps, with measurement and markup capabilities:
The MapMaker 1-Page Maps offer similar capabilities for standard line-drawing-style maps:
And MapMaker Kits are pre-packaged mapsets that can be printed out at wall or tabletop size (tiled sections that can be assembled into larger maps):
More info, and mapping activities, at the Mapping page of the site.