I’ve called before for a system of Universal DC Power and I still want it, but there is a partial step we could take.
I have a laptop power supply that comes with a variety of tips. The tips tell (through something as simple as a resistor) the power supply how much voltage and current to supply for the laptop they are designed for. I bought mine for use in an airplane, others are sold that do both 12v and AC power.
I would like to see one designed for the corporate market, rather than the carry-around market. Ones to be left in offices and under conference tables, so that when somebody visits with a laptop, they can plug it in. No need to get out their own supply or eventually no need to bring it.
Unlike the carry-around where you pick your tip and leave the rest, this would have an array of tips, possibly rotating on a click-wheel, or all connected to a switch where one can dial the voltage/polarity/etc.
Some companies take more drastic steps. At Google for example, I notice they have standardized on thinkpads, and so all desks and conference tables have think pad supplies. Everybody is able to roam the building and be sure of laptop power. These supplies, while a bit more expensive, could solve the same problem.
An alternate would be to standardize the special tip that describes the power needed. Everybody could get a tip or pigtail for their laptop and carry just that around. Conference rooms could in fact have single supplies that let you plug in several of the pigtail. Of course that is halfway to my original proposal.
Now it turns out a considerable majority of laptops take either 16 volts or 19 volts. The main rebel is Dell, which uses funny plugs and often over 20v. Some need more current than others, I don’t know if any need current limiting or if simply making the PS capable of 100w would do the trick. Anyway, in this case, we could develop a standard 16v plug (the thinkpad one) and a different standard 19v plug (probably an HP one), in two different shapes and colours, and people with laptops could carry a cheap converter to plug their laptop into it. Over time, laptops might come directly able to use this, if they aren’t already — on our path to a smarter power bus. Then people could say, “Oh, you have the orange plug. Great, I can plug my laptop into that.” Vendors who make laptops that won’t plug into one of these two will probably think about switching.