I've heard of apps that do that for meeting purposes.
Obviously I can't think of the names now.
How much money would be needed to be raised to start working on such an app?
We can start a campaign to collect money for such an app and I'm sure we can get some funding sources, we can start the campaign here on DDF and spread the word and explain the purpose of the app...
I would assume an average person's mindset is if there is 10 people great if there is not then also great, but now if an app would be established and one can be in the loop if there will be 10 people at this location at this time I'm sure I'll one would make it his business to run across the terminal to catch the minyan.
Mi kiamcha yisroel.. where ever we are always looking to help, even to help reach 10 for a minyan.