The SpaceSaver II keyboard originally made by IBM, presumably moved over to Lenovo at this point, has a very handy stick-mouse in the center of the keyboard.
Pro Quick access to a mouse, when it's occasionally needed
For those of us who generally avoid using the mouse, but occasionally require it for googling/stack-overflowing/closing-skype-popups, it's noticeably faster to not need to reach for it.
Only 14.5 inches wide, it is designed to use minimum desk space while offering maximum productivity. One of the main features to achieve this is removal of the numeric pad.
Con Not suitable for spreadsheet work
Since there's no numeric pad, this is not the best keyboard for number work.