The US Geological Survey's collection of historical topographic maps just got a whole lot easier to browse, thanks to USGS's recently-released online map viewer, topoView. The new interface was developed by Chris Garrity, a geographic information scientist at USGS, who wanted to make life easier for the two main groups of people hitting up the dated USGS website (in addition to USGS employees like Garrity who needed to easily access the maps for work):"People just looking for maps of their home town, and people who knew exactly what they wanted—this place, at this time, at this scale." The maps on the site are available for download free of charge, and represent topographical maps across the United States published between 1884 and 2006.
The interface is pretty much self-explanatory, but anyone needing a little extra assistance navigating the site can check out this handy YouTube introduction to topoView by Garrity himself. On the site, you can type in the name of the place you're searching for, or just zoom. The maps are available for download in a variety of formats, from JPGs to KMZ files (to import into Google Earth), and even GeoTIFFs.