A simple HTTP Server can be started in seconds.

python -m SimpleHTTPServer

For Python3:

python -m http.server

The server starts on port 8000 by default which can be changed. I have found this quite handy at times.

For example: To share a complete directory with someone over the Internet, I cd to the directory and start the server. The directory is shared, and I share my IP address. The directory can be viewed and files can be downloaded easily. I can also monitor access requests on the terminal.