Today's gadgets may meet with a yawn from some readers, but I recently learned that there are some poor souls out there who don't know about smooth-edge can openers, and they must be told.
Smooth-edge openers cut the can open from the side as opposed to the top, so the lid comes off with a smooth edge, rather than a jagged edge. Another advantage is that the cutting wheel never comes into contact with food, so less cleanup is involved.
There are several good smooth-edge openers available, including manual versions that work so well, you really don't need to bother with an electric model that has to be plugged in or recharged. Oxo and Zyliss both make decent manual openers, but I like Kuhn Rikon's the best, particularly the Auto Deluxe Safety Lid Lifter ($20), a really sturdy opener with a compact design and a reasonable price tag.
The Lid Lifter is easy to use once you figure out where to place the wheel on the can. If you do get confused, there's a useful demonstration video on Cooking.com. A bigger challenge, I think, is learning to use the side button to operate the pincers that lift off the can's lid. But they're hardly crucial, unless you really hate touching oily tuna-fish lids; and the guy in the video seems to have less trouble with the maneuver than I do.
Kuhn Rikon makes several other smooth-edge models, including one for left-handers that uses a pumping lever instead of a twisting knob. I'm a lefty, however, and have no trouble using the regular Lid Lifter.