The trick to de-icing perfection? For all the lazy bums out there, who can't handle the thorough (re: slow!) oven method, Aaron Mattis, of Serious Eats, breaks it down to a semi-science:
"Pizzerias reheat slices all the time, but their ovens are kept at scorching temperatures all day long. Reheating pizza in the oven or in a toaster oven on the bake setting takes more time than I'm willing to wait for a quick slice, especially since you need to use moderate heat to avoid burning the outside of a slice before the inside warms through. By contrast, toasting, though fast, often fails to heat a slice all the way through, especially if it has a thick crust.
After years of extensive research, I've hit on a solution: microwaving and then toasting.
By microwaving a slice, you heat it through quickly. By toasting it, you get a crisp crust in less than 5 minutes. If the slice is substantial enough, you can even put it directly on the grates of the toaster oven."
Good tip. For those who are still unclear, here's the HowTo, easy as 1-2-3: