Word Finder allows you to search for words based on patterns to make it easier to cheat at word games. For example, to search for all words that start with the letter a and enter end in the letter n, you can enter the query 'a-n'. You can also view the definitions for words, their scores in various word games, and save them as favourites.
Hipster Lab allows you to create custom Hipster faces. You can create yourself, friends, and celebrities easily and use them on your favorite social networks (including directly share to Instagram) to use as your avatar.
How well can you draw circles? When you are drawing on screen you are effectively drawing a many sided polygon, so from this I can calculate the internal area and the perimeter. Using that data, the area / radius^2 ratio can be found and the closer it is to π, the better. As a bonus you get a picture of a cat when you finish drawing, which is probably the only reason anyone ever downloaded it.
The regular iOS clock app sadly doesn't support running multiple timers at once (unlike the Android clock). Multi Timer allows you to save timers for things you do regularly, such as making tea, coffee, cooking, or running so that you can easily fire them without having to remember how long they are. As soon as a timer is finished you'll get a notification, regardless of whether the app is open.
Blurred Camera allows you to quickly take blurred photos or blur existing images with the option to customize the blur radius, the brightness and the saturation to create nice wallpapers for your iOS devices.
Redditors love celebrating their cake day (the anniversary of their reddit account) This app allows you to type in your reddit username and get annual reminders for your cake day.