You have to jailbreak to use Cydia. It has apps that have not been approved by Apple for various reasons.What is Cydia? I thought the App Store is only place to get apps.
My 10 fav:
Calendars by Readdle since it reads my activity in monthly view rather than only having a dot
Words with friends
Mind Snacks (Spanish)
Freecell Pro (play on mini iPad only--too small on iPhone)
Deep Sleep with Andrew Johnson