Topography

Working in an engineering office I find many new tools that I didn't know existed.  Today I found the USGS Topography map tool.  Using this tool you can look up current and historical topography maps anywhere in the U.S.  It's a great tool for looking at not only the topography but also the layout of roads from a particular era, and comparing how the roads changed over time.  This could be a very powerful tool for looking at the growth of cities, towns and unincorporated areas in the 20th Century.  The search is pretty intuitive, I started with only filling out the state field, Washington, and received over 4,000 hits.  I then ran a search for Poulsbo and received only 5 hits, so it pays to be exact and have an area you'd like to look at in mind.  Have a look and see you city in a different way.

Bonus feature: on the more recent maps they also contain aerial photography.