Cydia Tweaks from System Section
Send useful crash info to developers.
Powerful code insertion platform
BytaFont 3 lets you apply fonts to your iDevice in few taps.
Switch default browsers between Google Chrome, Opera Mini, iCab Mobile, Dolphing Browser, Atomic Browser, Diigo, iLunascape, MammothIV, Puffin, Mercury, Crux and Safari
Allow extensions to read the list of installed apps
Framework for managing lock screen plugins
Library support for Cycript in a UIWebView