ScreenPainter cydia tweak allows you to paint your screenshots before they are taken!
Just take a screenshot like normal, but after you press the buttons, draw. You can shake your device and it will give you the options to “Toggle Eraser”, “Change Color”, “Clear”, and “Add text box”. When editing a text box, shake to be given the options to delete or stop editing. Press the home button to select between “Keep Editing”, “Delete”, “Save to Camera Roll”, “Copy to Clipboard”, and combinations of the sorts.
You can also change the color of the screenshot flash!
Best functionality comes from iPads (bigger screens).