A couple of websites have come out recently that when combined with each other make a perfect storm of potential outcomes for geographers and historians alike.  Whilst some of them are not that old, they may be well known, but it is the combination of all three that has the greatest potential.  The first of these tools that I became aware of was http://dipity.com a grate time line tool that enables a user to create a linear set of events from pretty much any resource at their disposal on the internet.  Then came http://scribblemaps.com which enabled a user to overlay their own content onto a Google Maps page. Here the user can create shapes that might illustrate the phases of development, the alignment of troops on the battlefield overlaid on the modern topography.  In addition the user can then add their own text and images to the map.  The final tool in the triumvirate of tools is the newly launched http://historypin.com this tool encourages users to upload, link historic images of locations and places into a map and pin them to their actual location on the map.  These images can then be compared against the current Google Street view image (where possible) in order that a comparison or an evolution of images can be compared against the present.

Now using the different tools a user can not only put objects in a 2D space of a map but represent that same data in a linear time line and embed all of that information into one source such as a wiki.  Great for cause and effect and making links between information in space and time.  A perfect storm of tools.