Installous is an app used on jailbroken iPhones which you can use to easily locate, download and install cracked iPhone applications. It can be installed using Cydia from the cydia.hackulo.us repository. Installous provides a nice app store style interface with download links for cracked packages stored on popular file storage web sites (like MediaFire). It manages the downloads, stores the cracked IPA packages on the iPhone’s file system, and then installs them onto the iPhone. I also use AppSync which allows you to use iTunes to sync cracked IPA packages from your iTunes library and install them onto a jailbroken iPhone.
Installous provides an option for iTunes Sync but it does not always work as expected. If you install cracked apps using installous and then perform a sync in iTunes, you might run into a problem where iTunes removes the apps during a sync. You might also want to copy the cracked IPA packages which Installous downloads onto your iPhone to your iTunes library, but find that the packages are not backed up during a sync like other packages from the app store.
The solution is to first install the app with Installous and then connect the iPhone to the computer with iTunes. Right click on the iPhone under the left pane in iTunes and select “Transfer Purchases” (or left click to select the iPhone under the left pane and go to “File” –> “Transfer Purchases from … Phone” under the main iTunes menu). iTunes will copy the cracked apps into the iTunes library without any problems and they will no longer be deleted during the next sync.