update: the assessment of potentially extremely high cost-effectiveness mentioned at the end of this post seems no longer likely to be the case, unfortunately.

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Shawn VanDiver, director of a chapter of the Truman National Security Project, is coordinating with Arcis International and a coalition of folks trying to get as many people airlifted out of Afghanistan as they can. Apparently, the US is focused on getting its own citizens out, so this group is focused on getting Afghan nationals and non-US foreigners out.  From what I can see it seems to be a legitimate effort, if necessarily ad-hoc and hasty. VanDiver's tweets about this effort have been explicitly endorsed by Jack McCain, China Cyber and Intelligence Studies Institute's Joe McReynolds and Elsa Kania, and retweeted by the high-profile former U.S. ambassador Michael McFaul. 

Matt Bell has more details here, and quotes someone involved in the effort as follows:
"I'm part of a non-government group that's arranging chartered emergency flights out of Afghanistan for the Afghans who worked with us and are now at imminent risk of death. Assuming US forces hold the airport long enough, we've got the planes, we've got third country landing locations, what we need is funding. We've got pledges of about $100k so far, which will be enough to save about 200 people (that's about what one emergency flight costs) -- the more money, the more planes & thus Afghan lives we can save. This project is mostly national security folks with direct contacts working in their personal capacity, no one is making a cent off of it. If the plane isn't able to fly because the airport is overrun, you won't be out any money." He further says that the US is getting its own citizens out, so this group is focused on getting Afghan nationals and non-US foreigners out." 

At this point they are only requesting that people pledge how much they could donate via a Google Form, presumably to get a ballpark idea of how much money they hopefully would have to spend on chartered planes, as they do not want any money to actually be transferred to them until they can be sure that they have all the logistics in place. The form notes that "The company we are going through is Arcis International and they're working to secure the flight confirmation now. Upon confirmation we will have 24 hours to pay"; the time-sensitive nature of things is presumably why they request (optionally) a phone number.

At $100k for a flight to airlift 200 people, in theory many lives could be saved for as little as $500 each, although the numerous uncertainties involved suggest the cost-effectiveness is almost certainly less than that in reality. However, it still seems like potentially impactful way to help, and one of those situations where a relatively small amount of money could represent a tipping point at which another flight can be afforded or not.

The twitter thread with the form to pledge is available at https://twitter.com/shawnjvandiver/status/1427001848855105539 .