I have used the bottom of a Snowpeak 110 canister as a parabolic mirror to ignite tinder (shredded cedar bark) which I then used to light my campfire. Roll very finely shredded, very dry bark to create a "cigarette." Hold the end of the roll at the focal point in bright sunlight. When it ignites it will create a glowing ember. Place the ember in a "birdsnest" of more bark and gently blow it into flame. Place the flaming wad of bark under a pile of small dry twigs and add progressively larger sticks for a roaring fire.
I have tried the polished soda can trick, but it requires a tremendous amount of work, and all I ever got was small amounts of smoke. In a true survival situation, though, it would be worth pursuing if that was absolutely the only method available to make fire.
Incidently, I carry a credit-card size plastic Fresnel lens in my wallet as a potential survival tool. It has very reliably started many fires, although, obviously, one needs to have bright sunlight available for it to work.