In addition to give your accelerometer a second usage, your up and down volume buttons can also be used to scroll up and down; however, this could give your buttons a hard time.
If you are using iPad, you can enable manual scroll selection. This option will ask you in what scroll you want to activate PhyScroll, and it’s useful for applications that have multiple scrolls, like most of the iPad apps.
The tweak works on any scroll-enabled app for just $1.99. it`s also worth noting that this tweak works both on iOS 4 and the recent iOS 5 firmware.