An app highly similar to LockDown which allows you to lock your Cydia and AppStore apps. Add to that the option to lock your SIM card and option to encrypt files (photos, videos etc) on your iPhone or iPod touch such that they show-up only inside the application (this is a Paid feature appearing only when you buy the software).
The default password when you install mADvLock is 123. You should ideally go to settings and change the password first. The app features the App lock button on the lower left that allows you to unlock the system apps as well as Cydia and AppStore apps. Once you lock an App a green indicator next to the app would suggest that its has been locked. Once you have locked the desired apps, just press the home button to get out of ‘mad v Lock’.
Now as you try to access any App that is password protected it will first ask for an password. Of course you can always go back and remove password locking for any app.
The app is good, stable and useful. Go for it… even the free version is good enough!
To install this just search ‘mADvLock’ in Cydia
Cydia is a 3rd part apps aggregator / store, that Installs on Jailbroken iPhone 2G / 3G/ 3GS and iPod touch… Info here