I picked up a Logitech MX Revolution over the weekend.  Now all other mice are garbage.  
This thing has a two stage mouse wheel... spin it slow and it clicks like a normal wheel... give it a quick spin and the think kicks over into freewheel mode allowing you to blaze scroll through documents.  Getting back to the top of a page was never so easy!
Plus the think is ultra smooth, and the maybe the most comfortable mouse I've ever used.  It's the best $100 I ever spent on a mouse (that IGT will be reimbursing me for). 
 
 http://www.logitech.com/index.cfm/pr...volution_mxupp
http://www.logitech.com/index.cfm/pr...volution_mxupp