Cydia

Cydia is a full-featured graphical front end to APT and the dpkg package management system for the iOS developed by Jay Freeman (saurik). Cydia provides access to the latest software packages (including applications, themes, ringtones, and other modifications) exclusive to the jailbroken iPhone, iPod Touch, or iPad.

Cydia is typically installed on iOS devices during the jailbreaking process and includes a handful of default repositories known as community sources. These default repositories feature tens of thousands of software packages both free and commercially sold through the Cydia Store (similar to Apple's App Store). In addition to the already included community source repositories, Cydia also features a source manager allowing the addition of third-party or private repositories. These private repositories can be created by anyone with the will and means to run their own.
Although packages are easily navigated from any jailbroken iOS device through the Cydia application itself, Cydia Search is a browser-based search engine offering a quick and reliable alternative for finding packages currently available in Cydia.
Cydia Search checks all included repositories for new and updated packages once per hour. Additional information on how this system handles package data as well as asnwers to many frequently asked questions can be found on the FAQs page.