Track saws are good for ripping sheets of plywood, but the tracks are long and the systems require a dedicated saw. Kreg's Rip-Cut fence allows you to use a standard circular saw (sidewinder or wormdrive) to make straight rips in sheet goods and lumber. Just clip the saw in, slide the saw base to the desired spot on the rail, and lock it in place. The large guide arm prevents blade binding, and the unit is capable of ripping full sheets of plywood in half.
Price: $35. 800-447-8638. kregtool.com.