Apple has started a replacement program to fix MacBooks whose rubber surface is separating from the bottom case. The program covers MacBooks shipped between October 2009 and April 2011 that are exhibiting the problem. You can take an affected MacBook to an Apple Retail Store or Apple Authorized Service Provider to be fixed, or order a replacement kit online and do the work yourself. follow link
Option-Click in Scroll Bars for Jump Scrolling
In Mac OS X in general, and thus in most native Mac OS X applications, hold down the Option key and click anywhere in a window's scroll bar to jump to that spot (rather than scrolling one screen). If you like this behavior, you can make it the default in the Appearance preference pane. For "Click in the scroll bar to:" select "Jump to here."
MacBook Bottom Case Replacement Program