If you want to get free apps for the iPhone or iPod Touch, (for testing before purchasing of course) then you must first have your iPhone, iPad or iPod Touch jailbroken. Once you’re device is jailbroken, simply go on Cydia and add the Appcake repository seen below.
Cydia -> Manage -> Sources -> Edit -> Add
Once you’ve added the source and it has updated, you want to stay under sources and go into your new iPhoneCake Source that was just added. Install AppCake HD.
Now that it’s installed, you can go back to your springboard where you should find a new AppCake app. Go ahead and launch it and explore. If you cannot find a specific app you’re looking for, you may want to try the alternative vShare (formerly AppVV).