This was a special treat for me, being a huge fan of anyone who hacks a closed system to make it better. In this Origin Stories we learn how Jay Freeman (saurik) got started in programming and how he came to create Cydia.
Cydia is the premiere "alternative" apps venue outside Apple's own App Store. Jailbreak fans know it well, and yes, you must jailbreak your iPhone to use it.
But as jailbreakers know, using Cydia means having access to a plethora of useful tweaks and enhancements in iOS. If you've ever wanted more icons in your dock, or the ability to ignore a paired Bluetooth keyboard (our own Erica Sadun wrote up something for just that), Cydia's vast repositories of useful goodies will help you customize iOS to your heart's content.