It's probably one of the most well known and simplest ways of transferring files in an emergency. You simply pipe a file to a listening netcat service and have the client output the connection to a file.
Start/Share the file:
nc -l 5678 < file.blah
That line will start listening for connections on port 5678. Once a connection is made, it will spit out the contents of file.blah to the client. If you have the following netcat line listening on the "client" side then it will spit the contents it gets to a file:
nc example.com 5678 > file.blah
i like to md5 check the file afterward to make sure network gnomes didn't mess up the data somehow.
Pretty simple and straightforward.