I have straightened many a rotor from minor warps to sharp, severe bends where the rotor wouldn't slide through the caliper without pads. The drumstix are a very good system that takes some practice to master and is best used with a dial guage and a Park TS-2 truing stand. The cresent wrench is a decent alternative to the drumstix and if you've got three of 'em they can work very nearly as well on sharp bends.
Most of the warped rotors I see are gradual and when viewing the rotor between the pads with the wheel spining slowly the rotor seems to meander from one side to the other. In these cases I find the trouble spot, pinch a spoke next to it(it is important to work the point of greatest deviation as exactly as possible), rotate the wheel about 180 degrees to be sure you're not fighting the caliper or bending the rotor anywhere else, drop a clean rag over the rotor and bend it by hand. Why by hand? because the steel tools mentioned before isolate the forces at the edges of the jaws and create small sharp bends and/or divots in the rotor face. If the warp is gradual fix it by hand, if it's severe or sharp use tools. Either way, it's better to make 5 small corrections than 1 large overcorrection. Be careful and patient.