Timera is a clever photography app that is part photo-mashup app and part time machine that allows you to create impressive "then & now" photos of well-known locations.
The app uses your location information to pull up historic photos that are pulled from a growing database of user-submitted, geotagged images. You then align this old-time image with the real world and snap a photo that captures the modern day scene. You can blend the two images, allowing you yo create striking, haunting or amusing images that show how the area has changed over time. Like most photography apps, Timera has a social component that allows you to create a Timera profile as well as share these creative "Then and Now" photos with the Timera community and beyond.
Timera's biggest limitation is its database which contains only the most popular historic sites. You likely won't find a photo of your local town from the 1800s, but you will find content if you live in a large city like London. City dwellers can use the map and navigation tool as a guide, but there still is a fair amount of hunting and pecking to find exact locations with available historical images. When do find a supported location, Timera is a wonderfully creative tool.
Timera is available for free and is compatible with the iPhone running iOS 6 or later. There are no ads, but the app does require you to go through a registration process before you can use it.