Many Leatherman multi-tools include a combination bottle opener and can opener.

To use the Leatherman combination opener to remove a bottle cap, place the end on top of the cap, and hook the curved part under the rim of bottle cap. Then lift up.
To use it to open a tin can, place the hook under the rim of the can, and use the sharp portion to cut into the can, near the rim. Some of the bottle/can openers also include a sharpened notch near the base, that can be used for stripping insulation from electrical wires.
The combo opener varies slightly, but is generally about 33mm (1.25") in length.