Owners of old Mac laptops can join in on the fun of the newer laptops with this two-fingered scrolling trackpad driver. For the unfamiliar, two-finger scrolling means you press two fingers down on the trackpad and move up or down, and whatever you're looking at scrolls up or down. Essentially like the scroll wheel on a mouse.
Only install this on old laptops that don't have scrolling enabled. The new ones use a different trackpad that won't work.
Project Page [Sourceforge]