BusyBar is a new tweak available in Cydia that allows us to quickly and easily switch from one application to another using the iOS status bar. BusyBar displays the code name of the previously opened application in the status bar and with a tap (default) allows you to reopen that application. BusyBar has no icon in Springboard, but it can be modified using the iOS settings menu where it has a dedicated category. The tweak works through the activator plugin so you can set any gesture to switch to another application, the developer recommends setting a swype down.
BusyBar is available for free in Cydia.
