The MagSafe power adapter which is featured on all new Apple Notebooks is pretty much a great use of magnets.
It looks like they’ve made this very carefully. Not only is it stop the laptop from being smashed up when someone catches the power cable, but it is also symmetrical and so works two ways (the normal way and up-side down).
It also has a cool charge indicator built into the connector head, which takes the form of an LED which goes orange if the MacBook is charging and green if it’s already charged.
A clever design combined with good user feedback. It probably took a little more time to develop than my bog-standard IBM ThinkPad charger, but it was certainly worth it. The MagSafe power adapter is a strong selling point.