Studio
https://itunes.apple.com/us/app/studio-design/id671866502?mt=8
To quote Mashable:

MASHABLE: "What Instagram Did For Photography, This App Will Do For Design"

its a fun easy way to incorporate fun design elements into your photography - its for people who are not really designers, but want to be able to add text. masks, shapes to their photos in a very simple and easy to understand way.
Its free- and i had some fun playing on it over the past week!

Best
a