If you have a portable table saw, you know the limits. That little bitty table doesn't support sheet goods or long boards very well, and with most, you can only rip boards a foot or so wide. Here's how to make your saw cut anything the behemoth stationary saws can handle.
You'll need two hollow-core doors; any widths will do. We got ours from a building salvage company. New doors are available at home centers. Put them together and mark a notch 1/2 in. larger than the saw table. Cut out the notch, then carve out the cardboard webbing and glue in blocking to make the openings solid. Screw aluminum angle to the edge of the opening, placing its lip so the table saw surface will be even with the door tops. Add a couple of hinges for fold-up storage and you're ready to rip.
Clamp the saw to the aluminum angle so it's flush with both door bottoms. For really wide material, screw or clamp a straightedge to the door. Then remove it for the cut. Keep the fence parallel to the door edge. With this setup, my portable table saw works nearly as well as my Delta Unisaw.