How can I bring back the "bounce" when scrolling in OS X? I just system restored after a kernel panic, and I am no longer seeing this feature.  It used to be that when you scrolled (say, down this page in Firefox), there was some physics in the scroll, rather than a hard stop and start.  Since system restoring, this is gone.  How do I bring it back? I am using Snow Leopard.
I think you may be referring to the "Scroll with inertia" option, which is found in System Preferences > Trackpad. If it's set to scroll with inertia, but inertial scrolling isn't working, try toggling it to "without inertia" then back to "with inertia".

If that doesn't work, you can try deleting the preference file, "com.apple.driver.AppleBluetoothMultitouch.trackpad.plist" found in ~/Library/Preferences. Then log out, log back in and check the Trackpad preferences again.