ONE-SHOT is a "forkable conference" initially created by the organizer of NodeConf.
The main NodeConf events around the world are rather large productions and require a big commitment of time and financial risk. ONE-SHOT was created as a much simpler single day speaker series event that people around the world can pick up and run without a huge time commitment or considerable financial risk.
That first ONE-SHOT was run in London and events are now planned for Budapest, Brussels, and Oakland.
Ping @mikeal if you'd like to run an event, he'll give you instructions on how to fork the repository which includes the website, CFP instructions, and the Issue tracker can be used to accept talk proposals. Mikeal will also point "your city".nodeconf.com at the property gh-pages CNAME.