Roof repairs in the wake of a storm don't have to be pretty or permanent, as long as they save a house from further damage until a proper fix can be made.
Tin fix. For small holes, tuck a piece of aluminum flashing under the nearest intact shingle above the damage. Hold the flashing's lower edge in place with a roofing nail or two, and don't wait too long to replace it with a real shingle.
Quick-and-dirty tarping. In a pinch, drape a tarp over the ridge and fasten every grommet to the roof sheathing with a 2-inch screw and 11/2-inch fender washer. (You did charge your cordless drill before the storm, didn't you?)
Long-term tarping. When it will be months before a roofer can get to you, tarp for the long haul. First, cover the hole with 5/8-inch exterior-grade plywood, and fasten it to the undamaged sheathing with 2-inch deck screws. This will keep the tarp from collecting water and stop someone (a cat burglar, say) from accidentally falling through. Next, unfurl the tarp so one edge goes over the roof peak and a few feet down the other side. Doing this keeps water from running down under the tarp. Finally, secure the tarp's edges with 1x3 strapping, as shown at right, and screw them to the roof sheathing. The strapping will anchor the tarp securely until the pros arrive.
On tile roofs, which can't be screwed into, fasten the edges of tarps to the roof's rakes and eaves