Color Splash has been on the App Store for a very, very long time. Essentially, the app lets you take a full-color photo, highlight the part that you want to stand out, and make the entire image black and white except that specific point of focus. It's a cool effect, and not many apps can provide the same. But this senior member of the App Store has received a much-needed update, which you can download right now.
Version 3.0 of Color Splash updates the app to have an iOS 7 aesthetic, which gives it "a sleek new look and feel" according to the update notes. The update also packs a new "hue shift" adjustment slider which allows the user to change the colors slightly within the image being edited. Finally, the previously-removed option of displaying the outline of the brush while painting has been brought back.
You can get Color Splash, if you don't already have it, on the App Store for $0.99.