Here are the apps that I love! (These are for the iPhone because I have not jailbroken an iPad, or iPod Touch so I’m not sure if these work for them. Check out Cydia and see if they are also available to download. )
Design

WinterBoard- This is the first app you should download! This allows you to customize your device with themes!

BytaFont- Change your iPhone’s fonts

ColorKeyboard- Change the color of your Keyboard

Functionality

SB Settings – This app brings a super convenient dropdown menu, everytime you swipe the top of your phone. This means that from any app you can swipe, then change the brightness, turn wifi or 3g on or off, put it on airplane mode, etc. This eliminates the hassle of going to settings and pressing all these needless buttons.

Quick Reply App- Quick Reply is when you can reply to an incoming message without having to go to your sms app. I downloaded and bought the app iBiteSMS a while back and that included Quick Reply. I’m not sure which is the best Quick Reply app that’s free, but if you are willing to spend a few bucks for quality, I recommend you download iBiteSMS. In addition to Quick Reply, you can also Quick send a message. So what I do is just click on the volume button and it automatically pops up an sms box I can send messages, and also call, from. There is also a dropdown that displays your message history…