Quasar lets you Run Multiple Apps In Separate Windows Simultaneously On iPad

The Quasar Cydia tweak for iPad allows the user to open, position and resize multiple windows. Literally any app can be opened up and used in a floating window, or made fullscreen at the touch of a button. There are options to rotate the windows in case you want to change their orientation and you can configure the options for this tweak from the Settings menu.

Quaser is only available for jailbroken iPads running iOS 5 or higher and can be downloaded from the BigBoss repo on Cydia.