I would have thought that a more viable solution would have been invented by now, but at least finally it has.
Introduced at CES 2015 today was: The Dart.
A delivery of up to 60W of power with the ability to handle between 18-21V via 9 different interchangeable fittings. So no matter how many laptops you have in the house, chances are this one charger can take care of them all.
CNET has further details on pricing and pre-ordering if you are interested so head on over and check it out if this is your cup of tea.
Those who travel a lot or use their laptop for creating content will really appreciate this upgrade.