In pictures: 15 must-have iOS apps you can't get o...
Cal (iPhone, iPad and iPod touch)
The free Cal app for iOS takes your default calendar to the next level by pulling in your existing calendar and contacts information and incorporating it in a more visually appealing package. If you have a friend's image saved in your contacts, it's tied to any upcoming meetings or dates you may have with them. The app enriches each calendar event with maps and social integration, among other things. Its clean, streamlined interface makes navigation impressively simple.
In pictures: 15 must-have iOS apps you can't get on any other platform