If you hate reinstalling all of your jailbreak apps, extensions, and other hacks each time you re-jailbreak your iOS device, PkgBackup can help you automate the process and make life much easier. PKGBackup is a K.I.S.S. (Keep It Simple, Stupid) iOS application that backup/restore all Cydia packages, in additions to preferences & springboard files. It also support Categories & hidden files. Furthermore, you can now autobackup & schedule a backup.
PKGBacup is available for $9.99 in Cydia Store via BigBoss repo.