LongExpo is an app that allows you to have a longer shutter time that normal, which creates a very cool effect.
Here's the photo I took:
See how all the people that were moving at the time I took the photo, are faded, while the rest of the building stays sharp? That's the effect that long exposure has. I really like the way this photo turned out and can't wait to try it again!
For those interested, here you can find the app in the App Store:The app sadly does not seem to exist on Android, but I found a similar one: